# Kattis Problem Sources Alignment Report
This report documents all **Kattis problem sources** scraped from the live `open.kattis.com/problem-sources` index, classifying them into those successfully aligned to our ICPC contests and those unable to align.
**Total Scraped Sources:** 784
* **Aligned Sources:** 254
* **Unaligned Sources:** 530
## 🔗 Successfully Aligned Kattis Problem Sources
The following Kattis problem sources correspond directly to our tracked ICPC contests, including shared regional problem sets used across multiple regions:
| Kattis Problem Source Name | Aligned Contest(s) | Directory Acronym(s) | Live URL |
|---|---|---|---|
| Kattis Problem Source Name | Aligned Contest(s) | Directory Acronym(s) | Live URL |
|------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| 2000 ACM Mid-Central Regional Programming Contest | Mid-Central USA Regional Contest | `mcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/2000%20ACM%20Mid-Central%20Regional%20Programming%20Contest) |
| 2004 ACM ICPC Mid-Central North American Regional Contest | Mid-Central USA Regional Contest | `mcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/2004%20ACM%20ICPC%20Mid-Central%20North%20American%20Regional%20Contest) |
| 2008 ICPC North America Mid-Central Regional | Mid-Central USA Regional Contest | `mcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/2008%20ICPC%20North%20America%20Mid-Central%20Regional) |
| 2009 ACM Mid-Central USA Regional Programming Contest | Mid-Central USA Regional Contest | `mcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/2009%20ACM%20Mid-Central%20USA%20Regional%20Programming%20Contest) |
| 2012 University of Chicago Invitational Programming Contest | North American Invitational Programming Contest | `naipc` | [Open.Kattis](https://open.kattis.com/problem-sources/2012%20University%20of%20Chicago%20Invitational%20Programming%20Contest) |
| 2013 ACM-ICPC North American Qualifier | North America Qualifier | `naq` | [Open.Kattis](https://open.kattis.com/problem-sources/2013%20ACM-ICPC%20North%20American%20Qualifier) |
| 2013 University of Chicago Invitational Programming Contest | North American Invitational Programming Contest | `naipc` | [Open.Kattis](https://open.kattis.com/problem-sources/2013%20University%20of%20Chicago%20Invitational%20Programming%20Contest) |
| 2014 Greater New York Region ACM Regional Contest | Greater New York Regional Contest | `gnyr` | [Open.Kattis](https://open.kattis.com/problem-sources/2014%20Greater%20New%20York%20Region%20ACM%20Regional%20Contest) |
| 2014 ICPC North America Qualifier | North America Qualifier | `naq` | [Open.Kattis](https://open.kattis.com/problem-sources/2014%20ICPC%20North%20America%20Qualifier) |
| 2014 Southeast USA Regionals Division 1 | Southeast USA Regional Contest | `ser` | [Open.Kattis](https://open.kattis.com/problem-sources/2014%20Southeast%20USA%20Regionals%20Division%201) |
| 2015 Greater New York Region ACM Regional Contest | Greater New York Regional Contest | `gnyr` | [Open.Kattis](https://open.kattis.com/problem-sources/2015%20Greater%20New%20York%20Region%20ACM%20Regional%20Contest) |
| 2015 ICPC East-Central NA Regional Contest | East Central North America Regional Contest | `ecna` | [Open.Kattis](https://open.kattis.com/problem-sources/2015%20ICPC%20East-Central%20NA%20Regional%20Contest) |
| 2015 ICPC East-Central NA Regional Contest Practice Session | East Central North America Regional Contest | `ecna` | [Open.Kattis](https://open.kattis.com/problem-sources/2015%20ICPC%20East-Central%20NA%20Regional%20Contest%20Practice%20Session) |
| 2015 ICPC Mid-Central Regional | Mid-Central USA Regional Contest | `mcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/2015%20ICPC%20Mid-Central%20Regional) |
| 2015 ICPC North American Qualifier Contest | North America Qualifier | `naq` | [Open.Kattis](https://open.kattis.com/problem-sources/2015%20ICPC%20North%20American%20Qualifier%20Contest) |
| 2015 Southeast USA Regionals Division 1 | Southeast USA Regional Contest | `ser` | [Open.Kattis](https://open.kattis.com/problem-sources/2015%20Southeast%20USA%20Regionals%20Division%201) |
| 2016 Atlantic Canadian Preliminary Contest | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/2016%20Atlantic%20Canadian%20Preliminary%20Contest) |
| 2016 Greater New York Region ACM Regional Contest | Greater New York Regional Contest | `gnyr` | [Open.Kattis](https://open.kattis.com/problem-sources/2016%20Greater%20New%20York%20Region%20ACM%20Regional%20Contest) |
| 2016 ICPC East-Central NA Regional Contest | East Central North America Regional Contest | `ecna` | [Open.Kattis](https://open.kattis.com/problem-sources/2016%20ICPC%20East-Central%20NA%20Regional%20Contest) |
| 2016 ICPC Mid-Central Regional | Mid-Central USA Regional Contest | `mcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/2016%20ICPC%20Mid-Central%20Regional) |
| 2016 ICPC North American Qualifier Contest | North America Qualifier | `naq` | [Open.Kattis](https://open.kattis.com/problem-sources/2016%20ICPC%20North%20American%20Qualifier%20Contest) |
| 2016 Mid-Atlantic Regional | North American Mid-Atlantic Region | `midatl` | [Open.Kattis](https://open.kattis.com/problem-sources/2016%20Mid-Atlantic%20Regional) |
| 2016 Southeast USA Regionals Division 1 | Southeast USA Regional Contest | `ser` | [Open.Kattis](https://open.kattis.com/problem-sources/2016%20Southeast%20USA%20Regionals%20Division%201) |
| 2017 ACM ICPC North Central North America Regional Contest | North Central North America Regional Contest | `ncna` | [Open.Kattis](https://open.kattis.com/problem-sources/2017%20ACM%20ICPC%20North%20Central%20North%20America%20Regional%20Contest) |
| 2017 Atlantic Canadian Preliminary Contest | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/2017%20Atlantic%20Canadian%20Preliminary%20Contest) |
| 2017 Greater New York Region ACM Regional Contest | Greater New York Regional Contest | `gnyr` | [Open.Kattis](https://open.kattis.com/problem-sources/2017%20Greater%20New%20York%20Region%20ACM%20Regional%20Contest) |
| 2017 ICPC East-Central NA Regional Contest | East Central North America Regional Contest | `ecna` | [Open.Kattis](https://open.kattis.com/problem-sources/2017%20ICPC%20East-Central%20NA%20Regional%20Contest) |
| 2017 ICPC East-Central NA Regional Practice Contest | East Central North America Regional Contest | `ecna` | [Open.Kattis](https://open.kattis.com/problem-sources/2017%20ICPC%20East-Central%20NA%20Regional%20Practice%20Contest) |
| 2017 ICPC Mid-Atlantic Regional Contest | North American Mid-Atlantic Region | `midatl` | [Open.Kattis](https://open.kattis.com/problem-sources/2017%20ICPC%20Mid-Atlantic%20Regional%20Contest) |
| 2017 ICPC Mid-Atlantic Regional Practice Contest | North American Mid-Atlantic Region | `midatl` | [Open.Kattis](https://open.kattis.com/problem-sources/2017%20ICPC%20Mid-Atlantic%20Regional%20Practice%20Contest) |
| 2017 ICPC Mid-Central Regional | Mid-Central USA Regional Contest | `mcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/2017%20ICPC%20Mid-Central%20Regional) |
| 2017 ICPC North American Qualifier Contest | North America Qualifier | `naq` | [Open.Kattis](https://open.kattis.com/problem-sources/2017%20ICPC%20North%20American%20Qualifier%20Contest) |
| 2018 ACM-ICPC North Central North America Regional Contest | North Central North America Regional Contest | `ncna` | [Open.Kattis](https://open.kattis.com/problem-sources/2018%20ACM-ICPC%20North%20Central%20North%20America%20Regional%20Contest) |
| 2018 Atlantic Canadian Preliminary Contest | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/2018%20Atlantic%20Canadian%20Preliminary%20Contest) |
| 2018 ICPC East-Central NA Regional Contest | East Central North America Regional Contest | `ecna` | [Open.Kattis](https://open.kattis.com/problem-sources/2018%20ICPC%20East-Central%20NA%20Regional%20Contest) |
| 2018 ICPC East-Central NA Regional Practice Contest | East Central North America Regional Contest | `ecna` | [Open.Kattis](https://open.kattis.com/problem-sources/2018%20ICPC%20East-Central%20NA%20Regional%20Practice%20Contest) |
| 2018 ICPC Mid-Atlantic Regional Contest | North American Mid-Atlantic Region | `midatl` | [Open.Kattis](https://open.kattis.com/problem-sources/2018%20ICPC%20Mid-Atlantic%20Regional%20Contest) |
| 2018 ICPC Mid-Central Regional | Mid-Central USA Regional Contest | `mcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/2018%20ICPC%20Mid-Central%20Regional) |
| 2018 ICPC North American Qualifier Contest | North America Qualifier | `naq` | [Open.Kattis](https://open.kattis.com/problem-sources/2018%20ICPC%20North%20American%20Qualifier%20Contest) |
| 2018 ICPC South Central USA Regional Contest | South Central USA Regional Contest | `scusa` | [Open.Kattis](https://open.kattis.com/problem-sources/2018%20ICPC%20South%20Central%20USA%20Regional%20Contest) |
| 2019 Atlantic Canadian Preliminary Contest | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/2019%20Atlantic%20Canadian%20Preliminary%20Contest) |
| 2019 ICPC East-Central NA Regional Contest | East Central North America Regional Contest | `ecna` | [Open.Kattis](https://open.kattis.com/problem-sources/2019%20ICPC%20East-Central%20NA%20Regional%20Contest) |
| 2019 ICPC Greater New York Regional Programming Contest | Greater New York Regional Contest | `gnyr` | [Open.Kattis](https://open.kattis.com/problem-sources/2019%20ICPC%20Greater%20New%20York%20Regional%20Programming%20Contest) |
| 2019 ICPC Mid-Central Regional | Mid-Central USA Regional Contest | `mcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/2019%20ICPC%20Mid-Central%20Regional) |
| 2019 ICPC North American Qualifier Contest | North America Qualifier | `naq` | [Open.Kattis](https://open.kattis.com/problem-sources/2019%20ICPC%20North%20American%20Qualifier%20Contest) |
| 2019 ICPC Pacific Northwest Regional Programming Contest | Pacific Northwest Regional Contest | `pacnw` | [Open.Kattis](https://open.kattis.com/problem-sources/2019%20ICPC%20Pacific%20Northwest%20Regional%20Programming%20Contest) |
| 2019 ICPC Southeast USA Regional Programming Contest | Southeast USA Regional Contest | `ser` | [Open.Kattis](https://open.kattis.com/problem-sources/2019%20ICPC%20Southeast%20USA%20Regional%20Programming%20Contest) |
| 2019 ICPC Southern California Regional Programming Contest | Southern California Regional Contest | `socal` | [Open.Kattis](https://open.kattis.com/problem-sources/2019%20ICPC%20Southern%20California%20Regional%20Programming%20Contest) |
| 2019 PacNW Programming Contest | Pacific Northwest Regional Contest | `pacnw` | [Open.Kattis](https://open.kattis.com/problem-sources/2019%20PacNW%20Programming%20Contest) |
| 2020 ICPC East-Central NA Regional Contest | East Central North America Regional Contest | `ecna` | [Open.Kattis](https://open.kattis.com/problem-sources/2020%20ICPC%20East-Central%20NA%20Regional%20Contest) |
| 2020 ICPC North America Regionals (March 6 2021) | North American Mid-Atlantic Region
Southeast USA Regional Contest
South Central USA Regional Contest | `midatl`
`ser`
`scusa` | [Open.Kattis](https://open.kattis.com/problem-sources/2020%20ICPC%20North%20America%20Regionals%20%28March%206%202021%29) |
| 2020 ICPC North American Qualifier Contest | North America Qualifier | `naq` | [Open.Kattis](https://open.kattis.com/problem-sources/2020%20ICPC%20North%20American%20Qualifier%20Contest) |
| 2020-2021 North Central North America and Southern California ICPC Regional Contest | North Central North America Regional Contest | `ncna` | [Open.Kattis](https://open.kattis.com/problem-sources/2020-2021%20North%20Central%20North%20America%20and%20Southern%20California%20ICPC%20Regional%20Contest) |
| 2021 ICPC East-Central NA Regional Contest | East Central North America Regional Contest | `ecna` | [Open.Kattis](https://open.kattis.com/problem-sources/2021%20ICPC%20East-Central%20NA%20Regional%20Contest) |
| 2021 ICPC North America Division Championships | North America Division Championship | `nadc` | [Open.Kattis](https://open.kattis.com/problem-sources/2021%20ICPC%20North%20America%20Division%20Championships) |
| 2021 ICPC North America Regional Programming Contests (March 5 2022) | North American Mid-Atlantic Region
Southeast USA Regional Contest
South Central USA Regional Contest | `midatl`
`ser`
`scusa` | [Open.Kattis](https://open.kattis.com/problem-sources/2021%20ICPC%20North%20America%20Regional%20Programming%20Contests%20%28March%205%202022%29) |
| 2021 ICPC North America Regionals (February 26 2022) | North American Mid-Atlantic Region
Southeast USA Regional Contest
South Central USA Regional Contest | `midatl`
`ser`
`scusa` | [Open.Kattis](https://open.kattis.com/problem-sources/2021%20ICPC%20North%20America%20Regionals%20%28February%2026%202022%29) |
| 2021 ICPC North America Regionals Practice (March 5 2022) | North American Mid-Atlantic Region
Southeast USA Regional Contest
South Central USA Regional Contest | `midatl`
`ser`
`scusa` | [Open.Kattis](https://open.kattis.com/problem-sources/2021%20ICPC%20North%20America%20Regionals%20Practice%20%28March%205%202022%29) |
| 2021 ICPC North American Qualifier Contest (Jan 2022) | North America Qualifier | `naq` | [Open.Kattis](https://open.kattis.com/problem-sources/2021%20ICPC%20North%20American%20Qualifier%20Contest%20%28Jan%202022%29) |
| 2021/2022 Southern California Regional ICPC | Southern California Regional Contest | `socal` | [Open.Kattis](https://open.kattis.com/problem-sources/2021/2022%20Southern%20California%20Regional%20ICPC) |
| 2022 ICPC North America Championship | North America Championship | `nac` | [Open.Kattis](https://open.kattis.com/problem-sources/2022%20ICPC%20North%20America%20Championship) |
| 2022 ICPC North America Championship Practice | North America Championship | `nac` | [Open.Kattis](https://open.kattis.com/problem-sources/2022%20ICPC%20North%20America%20Championship%20Practice) |
| 2022 ICPC North America Qualifier | North America Qualifier | `naq` | [Open.Kattis](https://open.kattis.com/problem-sources/2022%20ICPC%20North%20America%20Qualifier) |
| 2022 ICPC North America Regional Contests (February 25, 2023) | North American Mid-Atlantic Region
Southeast USA Regional Contest
South Central USA Regional Contest
East Central North America Regional Contest
Greater New York Regional Contest | `midatl`
`ser`
`scusa`
`ecna`
`gnyr` | [Open.Kattis](https://open.kattis.com/problem-sources/2022%20ICPC%20North%20America%20Regional%20Contests%20%28February%2025%2C%202023%29) |
| 2022 ICPC North America Regional Programming Contests (February 25, 2023) | North American Mid-Atlantic Region
Southeast USA Regional Contest
South Central USA Regional Contest
East Central North America Regional Contest
Greater New York Regional Contest | `midatl`
`ser`
`scusa`
`ecna`
`gnyr` | [Open.Kattis](https://open.kattis.com/problem-sources/2022%20ICPC%20North%20America%20Regional%20Programming%20Contests%20%28February%2025%2C%202023%29) |
| 2023 ICPC North America Championship | North America Championship | `nac` | [Open.Kattis](https://open.kattis.com/problem-sources/2023%20ICPC%20North%20America%20Championship) |
| 2023 ICPC North America Qualifier 30 September | North America Qualifier | `naq` | [Open.Kattis](https://open.kattis.com/problem-sources/2023%20ICPC%20North%20America%20Qualifier%2030%20September) |
| 2023 ICPC North America Regional Programming Contests (February 24, 2024) | North American Mid-Atlantic Region
Southeast USA Regional Contest
South Central USA Regional Contest | `midatl`
`ser`
`scusa` | [Open.Kattis](https://open.kattis.com/problem-sources/2023%20ICPC%20North%20America%20Regional%20Programming%20Contests%20%28February%2024%2C%202024%29) |
| 2023 North America East Division Contest | Northeast North America Regional Contest
Greater New York Regional Contest
East Central North America Regional Contest | `nane`
`gnyr`
`ecna` | [Open.Kattis](https://open.kattis.com/problem-sources/2023%20North%20America%20East%20Division%20Contest) |
| 2024 ICPC East Central North America Regional | East Central North America Regional Contest | `ecna` | [Open.Kattis](https://open.kattis.com/problem-sources/2024%20ICPC%20East%20Central%20North%20America%20Regional) |
| 2024 ICPC North America Championship | North America Championship | `nac` | [Open.Kattis](https://open.kattis.com/problem-sources/2024%20ICPC%20North%20America%20Championship) |
| 2024 ICPC North America Qualifier | North America Qualifier | `naq` | [Open.Kattis](https://open.kattis.com/problem-sources/2024%20ICPC%20North%20America%20Qualifier) |
| 2024 ICPC Pacific Northwest Regional (November 16, 2024) | Pacific Northwest Regional Contest | `pacnw` | [Open.Kattis](https://open.kattis.com/problem-sources/2024%20ICPC%20Pacific%20Northwest%20Regional%20%28November%2016%2C%202024%29) |
| 2024 ICPC South Central, South East and Mid Atlantic Regional (November 16, 2024) | North American Mid-Atlantic Region
Southeast USA Regional Contest
South Central USA Regional Contest | `midatl`
`ser`
`scusa` | [Open.Kattis](https://open.kattis.com/problem-sources/2024%20ICPC%20South%20Central%2C%20South%20East%20and%20Mid%20Atlantic%20Regional%20%28November%2016%2C%202024%29) |
| 2024 North America East Division Contest | Northeast North America Regional Contest
Greater New York Regional Contest
East Central North America Regional Contest | `nane`
`gnyr`
`ecna` | [Open.Kattis](https://open.kattis.com/problem-sources/2024%20North%20America%20East%20Division%20Contest) |
| 2025 ICPC North America Central Division | Mid-Central USA Regional Contest
North Central North America Regional Contest | `mcpc`
`ncna` | [Open.Kattis](https://open.kattis.com/problem-sources/2025%20ICPC%20North%20America%20Central%20Division) |
| 2025 ICPC North America Championship | North America Championship | `nac` | [Open.Kattis](https://open.kattis.com/problem-sources/2025%20ICPC%20North%20America%20Championship) |
| 2025 ICPC North America Mid-Central Regional | Mid-Central USA Regional Contest | `mcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/2025%20ICPC%20North%20America%20Mid-Central%20Regional) |
| 2025 ICPC North America Qualifier | North America Qualifier | `naq` | [Open.Kattis](https://open.kattis.com/problem-sources/2025%20ICPC%20North%20America%20Qualifier) |
| 2025 ICPC South Central, South East and Mid Atlantic Regional (November 8, 2025) | North American Mid-Atlantic Region
Southeast USA Regional Contest
South Central USA Regional Contest | `midatl`
`ser`
`scusa` | [Open.Kattis](https://open.kattis.com/problem-sources/2025%20ICPC%20South%20Central%2C%20South%20East%20and%20Mid%20Atlantic%20Regional%20%28November%208%2C%202025%29) |
| 2025 North America East Division Contest | Northeast North America Regional Contest
Greater New York Regional Contest
East Central North America Regional Contest | `nane`
`gnyr`
`ecna` | [Open.Kattis](https://open.kattis.com/problem-sources/2025%20North%20America%20East%20Division%20Contest) |
| 2026 ICPC North America Championship | North America Championship | `nac` | [Open.Kattis](https://open.kattis.com/problem-sources/2026%20ICPC%20North%20America%20Championship) |
| ACM-ICPC World Finals 2019 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/ACM-ICPC%20World%20Finals%202019) |
| ACM/ICPC Mid-Central USA 2014 Regional Contest | Mid-Central USA Regional Contest | `mcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/ACM/ICPC%20Mid-Central%20USA%202014%20Regional%20Contest) |
| Benelux Algorithm Programming Contest (BAPC) 2012 | Benelux Algorithm Programming Contest (BAPC) | `bapc` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%202012) |
| Benelux Algorithm Programming Contest (BAPC) 2013 | Benelux Algorithm Programming Contest (BAPC) | `bapc` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%202013) |
| Benelux Algorithm Programming Contest (BAPC) 2014 | Benelux Algorithm Programming Contest (BAPC) | `bapc` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%202014) |
| Benelux Algorithm Programming Contest (BAPC) 2015 | Benelux Algorithm Programming Contest (BAPC) | `bapc` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%202015) |
| Benelux Algorithm Programming Contest (BAPC) 2016 | Benelux Algorithm Programming Contest (BAPC) | `bapc` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%202016) |
| Benelux Algorithm Programming Contest (BAPC) 2017 | Benelux Algorithm Programming Contest (BAPC) | `bapc` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%202017) |
| Benelux Algorithm Programming Contest (BAPC) 2018 | Benelux Algorithm Programming Contest (BAPC) | `bapc` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%202018) |
| Benelux Algorithm Programming Contest (BAPC) 2019 | Benelux Algorithm Programming Contest (BAPC) | `bapc` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%202019) |
| Benelux Algorithm Programming Contest (BAPC) 2020 | Benelux Algorithm Programming Contest (BAPC) | `bapc` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%202020) |
| Benelux Algorithm Programming Contest (BAPC) 2021 | Benelux Algorithm Programming Contest (BAPC) | `bapc` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%202021) |
| Benelux Algorithm Programming Contest (BAPC) 2022 | Benelux Algorithm Programming Contest (BAPC) | `bapc` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%202022) |
| Benelux Algorithm Programming Contest (BAPC) 2023 | Benelux Algorithm Programming Contest (BAPC) | `bapc` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%202023) |
| Benelux Algorithm Programming Contest (BAPC) 2024 | Benelux Algorithm Programming Contest (BAPC) | `bapc` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%202024) |
| Benelux Algorithm Programming Contest (BAPC) 2025 | Benelux Algorithm Programming Contest (BAPC) | `bapc` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%202025) |
| Benelux Algorithm Programming Contest (BAPC) preliminaries 2016 | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%20preliminaries%202016) |
| Benelux Algorithm Programming Contest (BAPC) preliminaries 2017 | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%20preliminaries%202017) |
| Benelux Algorithm Programming Contest (BAPC) preliminaries 2018 | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%20preliminaries%202018) |
| Benelux Algorithm Programming Contest (BAPC) preliminaries 2019 | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%20preliminaries%202019) |
| Benelux Algorithm Programming Contest (BAPC) preliminaries 2020 | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%20preliminaries%202020) |
| Benelux Algorithm Programming Contest (BAPC) preliminaries 2021 | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%20preliminaries%202021) |
| Benelux Algorithm Programming Contest (BAPC) preliminaries 2022 | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%20preliminaries%202022) |
| Benelux Algorithm Programming Contest (BAPC) preliminaries 2023 | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%20preliminaries%202023) |
| Benelux Algorithm Programming Contest (BAPC) preliminaries 2024 | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%20preliminaries%202024) |
| Benelux Algorithm Programming Contest (BAPC) preliminaries 2025 | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/Benelux%20Algorithm%20Programming%20Contest%20%28BAPC%29%20preliminaries%202025) |
| CTU Open 2005 | Czech Technical University Open (CTU Open) | `ctuopen` | [Open.Kattis](https://open.kattis.com/problem-sources/CTU%20Open%202005) |
| CTU Open 2008 | Czech Technical University Open (CTU Open) | `ctuopen` | [Open.Kattis](https://open.kattis.com/problem-sources/CTU%20Open%202008) |
| CTU Open 2009 | Czech Technical University Open (CTU Open) | `ctuopen` | [Open.Kattis](https://open.kattis.com/problem-sources/CTU%20Open%202009) |
| CTU Open 2010 | Czech Technical University Open (CTU Open) | `ctuopen` | [Open.Kattis](https://open.kattis.com/problem-sources/CTU%20Open%202010) |
| CTU Open 2011 | Czech Technical University Open (CTU Open) | `ctuopen` | [Open.Kattis](https://open.kattis.com/problem-sources/CTU%20Open%202011) |
| CTU Open 2012 | Czech Technical University Open (CTU Open) | `ctuopen` | [Open.Kattis](https://open.kattis.com/problem-sources/CTU%20Open%202012) |
| CTU Open 2013 | Czech Technical University Open (CTU Open) | `ctuopen` | [Open.Kattis](https://open.kattis.com/problem-sources/CTU%20Open%202013) |
| CTU Open 2015 | Czech Technical University Open (CTU Open) | `ctuopen` | [Open.Kattis](https://open.kattis.com/problem-sources/CTU%20Open%202015) |
| CTU Open 2021 | Czech Technical University Open (CTU Open) | `ctuopen` | [Open.Kattis](https://open.kattis.com/problem-sources/CTU%20Open%202021) |
| Central Europe Regional Contest (CERC) 2010 | Central Europe Regional Contest | `cerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Central%20Europe%20Regional%20Contest%20%28CERC%29%202010) |
| Central Europe Regional Contest (CERC) 2012 | Central Europe Regional Contest | `cerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Central%20Europe%20Regional%20Contest%20%28CERC%29%202012) |
| Central Europe Regional Contest (CERC) 2013 | Central Europe Regional Contest | `cerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Central%20Europe%20Regional%20Contest%20%28CERC%29%202013) |
| Central Europe Regional Contest (CERC) 2014 | Central Europe Regional Contest | `cerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Central%20Europe%20Regional%20Contest%20%28CERC%29%202014) |
| Central Europe Regional Contest (CERC) 2015 | Central Europe Regional Contest | `cerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Central%20Europe%20Regional%20Contest%20%28CERC%29%202015) |
| Central Europe Regional Contest (CERC) 2016 | Central Europe Regional Contest | `cerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Central%20Europe%20Regional%20Contest%20%28CERC%29%202016) |
| German Collegiate Programming Contest (GCPC) 2011 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202011) |
| German Collegiate Programming Contest (GCPC) 2012 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202012) |
| German Collegiate Programming Contest (GCPC) 2013 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202013) |
| German Collegiate Programming Contest (GCPC) 2014 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202014) |
| German Collegiate Programming Contest (GCPC) 2015 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202015) |
| German Collegiate Programming Contest (GCPC) 2016 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202016) |
| German Collegiate Programming Contest (GCPC) 2017 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202017) |
| German Collegiate Programming Contest (GCPC) 2018 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202018) |
| German Collegiate Programming Contest (GCPC) 2019 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202019) |
| German Collegiate Programming Contest (GCPC) 2020 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202020) |
| German Collegiate Programming Contest (GCPC) 2021 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202021) |
| German Collegiate Programming Contest (GCPC) 2022 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202022) |
| German Collegiate Programming Contest (GCPC) 2023 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202023) |
| German Collegiate Programming Contest (GCPC) 2024 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202024) |
| German Collegiate Programming Contest (GCPC) 2025 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202025) |
| German Collegiate Programming Contest (GCPC) 2026 | German Collegiate Programming Championship | `gcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/German%20Collegiate%20Programming%20Contest%20%28GCPC%29%202026) |
| Google Code Jam 2008 World Finals | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202008%20World%20Finals) |
| Google Code Jam World Finals 2010 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/Google%20Code%20Jam%20World%20Finals%202010) |
| Hong Kong Regional Online Preliminary 2016 | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/Hong%20Kong%20Regional%20Online%20Preliminary%202016) |
| ICPC 2012 North American Qualifier | North America Qualifier | `naq` | [Open.Kattis](https://open.kattis.com/problem-sources/ICPC%202012%20North%20American%20Qualifier) |
| ICPC NCNA Regionals 2025 2026 | North Central North America Regional Contest | `ncna` | [Open.Kattis](https://open.kattis.com/problem-sources/ICPC%20NCNA%20Regionals%202025%202026) |
| ICPC North America Championship 2021 | North America Championship | `nac` | [Open.Kattis](https://open.kattis.com/problem-sources/ICPC%20North%20America%20Championship%202021) |
| ICPC North America Regional Contests 2019-11-09 | North American Mid-Atlantic Region
Southeast USA Regional Contest
South Central USA Regional Contest | `midatl`
`ser`
`scusa` | [Open.Kattis](https://open.kattis.com/problem-sources/ICPC%20North%20America%20Regional%20Contests%202019-11-09) |
| ICPC SG Preliminary Contest 2015 | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/ICPC%20SG%20Preliminary%20Contest%202015) |
| ICPC SG Preliminary Contest 2018 | Benelux Algorithm Programming Championship Preliminaries (BAPC Prelims) | `bapc-prelim` | [Open.Kattis](https://open.kattis.com/problem-sources/ICPC%20SG%20Preliminary%20Contest%202018) |
| ICPC World Finals 2020 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/ICPC%20World%20Finals%202020) |
| ICPC World Finals 2021 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/ICPC%20World%20Finals%202021) |
| ICPC World Finals 2022 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/ICPC%20World%20Finals%202022) |
| ICPC World Finals 2022 and 2023 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/ICPC%20World%20Finals%202022%20and%202023) |
| ICPC World Finals 2023 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/ICPC%20World%20Finals%202023) |
| ICPC World Finals 2024 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/ICPC%20World%20Finals%202024) |
| ICPC World Finals 2025 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/ICPC%20World%20Finals%202025) |
| ICPC/SWERC 2025 | Southwestern Europe Regional Contest | `swerc` | [Open.Kattis](https://open.kattis.com/problem-sources/ICPC/SWERC%202025) |
| International Collegiate Programming Contest (ACM-ICPC) World Finals 2012 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/International%20Collegiate%20Programming%20Contest%20%28ACM-ICPC%29%20World%20Finals%202012) |
| International Collegiate Programming Contest (ACM-ICPC) World Finals 2013 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/International%20Collegiate%20Programming%20Contest%20%28ACM-ICPC%29%20World%20Finals%202013) |
| International Collegiate Programming Contest (ACM-ICPC) World Finals 2014 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/International%20Collegiate%20Programming%20Contest%20%28ACM-ICPC%29%20World%20Finals%202014) |
| International Collegiate Programming Contest (ACM-ICPC) World Finals 2015 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/International%20Collegiate%20Programming%20Contest%20%28ACM-ICPC%29%20World%20Finals%202015) |
| International Collegiate Programming Contest (ACM-ICPC) World Finals 2016 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/International%20Collegiate%20Programming%20Contest%20%28ACM-ICPC%29%20World%20Finals%202016) |
| International Collegiate Programming Contest (ACM-ICPC) World Finals 2017 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/International%20Collegiate%20Programming%20Contest%20%28ACM-ICPC%29%20World%20Finals%202017) |
| International Collegiate Programming Contest (ACM-ICPC) World Finals 2018 | ICPC World Finals | `finals` | [Open.Kattis](https://open.kattis.com/problem-sources/International%20Collegiate%20Programming%20Contest%20%28ACM-ICPC%29%20World%20Finals%202018) |
| Italian Collegiate Programming Contest 2022 | Italian Collegiate Programming Contest (ITACPC) | `itacpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Italian%20Collegiate%20Programming%20Contest%202022) |
| Mid-Central Regional Programming Contest 2024 | Mid-Central USA Regional Contest | `mcpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Mid-Central%20Regional%20Programming%20Contest%202024) |
| NCPC 2012 and KTH training | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/NCPC%202012%20and%20KTH%20training) |
| NENA 2019 | Northeast North America Regional Contest | `nane` | [Open.Kattis](https://open.kattis.com/problem-sources/NENA%202019) |
| Nordic Collegiate Programming Contest (NCPC) 2005 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202005) |
| Nordic Collegiate Programming Contest (NCPC) 2006 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202006) |
| Nordic Collegiate Programming Contest (NCPC) 2007 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202007) |
| Nordic Collegiate Programming Contest (NCPC) 2008 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202008) |
| Nordic Collegiate Programming Contest (NCPC) 2008, adapted from Andrew Stankevich Contest 17, Petrozavodsk, February 2, 2006 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202008%2C%20adapted%20from%20Andrew%20Stankevich%20Contest%2017%2C%20Petrozavodsk%2C%20February%202%2C%202006) |
| Nordic Collegiate Programming Contest (NCPC) 2009 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202009) |
| Nordic Collegiate Programming Contest (NCPC) 2010 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202010) |
| Nordic Collegiate Programming Contest (NCPC) 2011 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202011) |
| Nordic Collegiate Programming Contest (NCPC) 2012 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202012) |
| Nordic Collegiate Programming Contest (NCPC) 2013 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202013) |
| Nordic Collegiate Programming Contest (NCPC) 2014 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202014) |
| Nordic Collegiate Programming Contest (NCPC) 2015 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202015) |
| Nordic Collegiate Programming Contest (NCPC) 2016 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202016) |
| Nordic Collegiate Programming Contest (NCPC) 2017 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202017) |
| Nordic Collegiate Programming Contest (NCPC) 2018 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202018) |
| Nordic Collegiate Programming Contest (NCPC) 2019 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202019) |
| Nordic Collegiate Programming Contest (NCPC) 2020 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202020) |
| Nordic Collegiate Programming Contest (NCPC) 2021 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202021) |
| Nordic Collegiate Programming Contest (NCPC) 2022 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202022) |
| Nordic Collegiate Programming Contest (NCPC) 2023 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202023) |
| Nordic Collegiate Programming Contest (NCPC) 2024 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202024) |
| Nordic Collegiate Programming Contest (NCPC) 2025 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202025) |
| Nordic Collegiate Programming Contest (NCPC) 2026 | Nordic Collegiate Programming Contest | `ncpc` | [Open.Kattis](https://open.kattis.com/problem-sources/Nordic%20Collegiate%20Programming%20Contest%20%28NCPC%29%202026) |
| North America Championship 2020 | North America Championship | `nac` | [Open.Kattis](https://open.kattis.com/problem-sources/North%20America%20Championship%202020) |
| North American Invitational Programming Contest (NAIPC) 2014 | North American Invitational Programming Contest | `naipc` | [Open.Kattis](https://open.kattis.com/problem-sources/North%20American%20Invitational%20Programming%20Contest%20%28NAIPC%29%202014) |
| North American Invitational Programming Contest (NAIPC) 2015 | North American Invitational Programming Contest | `naipc` | [Open.Kattis](https://open.kattis.com/problem-sources/North%20American%20Invitational%20Programming%20Contest%20%28NAIPC%29%202015) |
| North American Invitational Programming Contest (NAIPC) 2016 | North American Invitational Programming Contest | `naipc` | [Open.Kattis](https://open.kattis.com/problem-sources/North%20American%20Invitational%20Programming%20Contest%20%28NAIPC%29%202016) |
| North American Invitational Programming Contest (NAIPC) 2017 | North American Invitational Programming Contest | `naipc` | [Open.Kattis](https://open.kattis.com/problem-sources/North%20American%20Invitational%20Programming%20Contest%20%28NAIPC%29%202017) |
| North American Invitational Programming Contest (NAIPC) 2018 | North American Invitational Programming Contest | `naipc` | [Open.Kattis](https://open.kattis.com/problem-sources/North%20American%20Invitational%20Programming%20Contest%20%28NAIPC%29%202018) |
| North American Invitational Programming Contest (NAIPC) 2019 | North American Invitational Programming Contest | `naipc` | [Open.Kattis](https://open.kattis.com/problem-sources/North%20American%20Invitational%20Programming%20Contest%20%28NAIPC%29%202019) |
| North Central North America Regional Contest 2023 | North Central North America Regional Contest | `ncna` | [Open.Kattis](https://open.kattis.com/problem-sources/North%20Central%20North%20America%20Regional%20Contest%202023) |
| North Central North America Regional Programming Contest 2023 | North Central North America Regional Contest | `ncna` | [Open.Kattis](https://open.kattis.com/problem-sources/North%20Central%20North%20America%20Regional%20Programming%20Contest%202023) |
| North Central Regional Programming Contest 2024 | North Central North America Regional Contest | `ncna` | [Open.Kattis](https://open.kattis.com/problem-sources/North%20Central%20Regional%20Programming%20Contest%202024) |
| Northeast North America Regional 2013 | Northeast North America Regional Contest | `nane` | [Open.Kattis](https://open.kattis.com/problem-sources/Northeast%20North%20America%20Regional%202013) |
| Northeast North America Regional 2014 | Northeast North America Regional Contest | `nane` | [Open.Kattis](https://open.kattis.com/problem-sources/Northeast%20North%20America%20Regional%202014) |
| Northwestern Europe Contest (NWERC) 2008 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Contest%20%28NWERC%29%202008) |
| Northwestern Europe Contest (NWERC) 2009 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Contest%20%28NWERC%29%202009) |
| Northwestern Europe Programming Contest (NWERC) 2003 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Programming%20Contest%20%28NWERC%29%202003) |
| Northwestern Europe Programming Contest (NWERC) 2004 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Programming%20Contest%20%28NWERC%29%202004) |
| Northwestern Europe Programming Contest (NWERC) 2005 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Programming%20Contest%20%28NWERC%29%202005) |
| Northwestern Europe Programming Contest (NWERC) 2006 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Programming%20Contest%20%28NWERC%29%202006) |
| Northwestern Europe Regional Contest (NWERC) 2010 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202010) |
| Northwestern Europe Regional Contest (NWERC) 2011 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202011) |
| Northwestern Europe Regional Contest (NWERC) 2014 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202014) |
| Northwestern Europe Regional Contest (NWERC) 2014 Practice Session | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202014%20Practice%20Session) |
| Northwestern Europe Regional Contest (NWERC) 2015 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202015) |
| Northwestern Europe Regional Contest (NWERC) 2015 Practice | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202015%20Practice) |
| Northwestern Europe Regional Contest (NWERC) 2016 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202016) |
| Northwestern Europe Regional Contest (NWERC) 2017 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202017) |
| Northwestern Europe Regional Contest (NWERC) 2018 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202018) |
| Northwestern Europe Regional Contest (NWERC) 2019 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202019) |
| Northwestern Europe Regional Contest (NWERC) 2020 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202020) |
| Northwestern Europe Regional Contest (NWERC) 2021 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202021) |
| Northwestern Europe Regional Contest (NWERC) 2022 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202022) |
| Northwestern Europe Regional Contest (NWERC) 2023 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202023) |
| Northwestern Europe Regional Contest (NWERC) 2024 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202024) |
| Northwestern Europe Regional Contest (NWERC) 2025 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20Europe%20Regional%20Contest%20%28NWERC%29%202025) |
| Northwestern European Programming Contest (NWERC) 2007 | Northwestern Europe Regional Contest | `nwerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Northwestern%20European%20Programming%20Contest%20%28NWERC%29%202007) |
| Rocky Mountain Regional Contest (RMRC) 2013 | Rocky Mountain Regional Contest | `rmrc` | [Open.Kattis](https://open.kattis.com/problem-sources/Rocky%20Mountain%20Regional%20Contest%20%28RMRC%29%202013) |
| Rocky Mountain Regional Contest (RMRC) 2014 | Rocky Mountain Regional Contest | `rmrc` | [Open.Kattis](https://open.kattis.com/problem-sources/Rocky%20Mountain%20Regional%20Contest%20%28RMRC%29%202014) |
| Rocky Mountain Regional Contest (RMRC) 2015 | Rocky Mountain Regional Contest | `rmrc` | [Open.Kattis](https://open.kattis.com/problem-sources/Rocky%20Mountain%20Regional%20Contest%20%28RMRC%29%202015) |
| Rocky Mountain Regional Contest (RMRC) 2016 | Rocky Mountain Regional Contest | `rmrc` | [Open.Kattis](https://open.kattis.com/problem-sources/Rocky%20Mountain%20Regional%20Contest%20%28RMRC%29%202016) |
| Rocky Mountain Regional Contest (RMRC) 2017 | Rocky Mountain Regional Contest | `rmrc` | [Open.Kattis](https://open.kattis.com/problem-sources/Rocky%20Mountain%20Regional%20Contest%20%28RMRC%29%202017) |
| Rocky Mountain Regional Programming Contest 2018 | Rocky Mountain Regional Contest | `rmrc` | [Open.Kattis](https://open.kattis.com/problem-sources/Rocky%20Mountain%20Regional%20Programming%20Contest%202018) |
| Rocky Mountain Regional Programming Contest 2019 | Rocky Mountain Regional Contest | `rmrc` | [Open.Kattis](https://open.kattis.com/problem-sources/Rocky%20Mountain%20Regional%20Programming%20Contest%202019) |
| Rocky Mountain Regional Programming Contest 2020 | Rocky Mountain Regional Contest | `rmrc` | [Open.Kattis](https://open.kattis.com/problem-sources/Rocky%20Mountain%20Regional%20Programming%20Contest%202020) |
| Rocky Mountain Regional Programming Contest 2021 | Rocky Mountain Regional Contest | `rmrc` | [Open.Kattis](https://open.kattis.com/problem-sources/Rocky%20Mountain%20Regional%20Programming%20Contest%202021) |
| Rocky Mountain Regional Programming Contest 2023 | Rocky Mountain Regional Contest | `rmrc` | [Open.Kattis](https://open.kattis.com/problem-sources/Rocky%20Mountain%20Regional%20Programming%20Contest%202023) |
| Rocky Mountain Regional Programming Contest 2024 | Rocky Mountain Regional Contest | `rmrc` | [Open.Kattis](https://open.kattis.com/problem-sources/Rocky%20Mountain%20Regional%20Programming%20Contest%202024) |
| Rocky Mountain Regional Programming Contest 2025 | Rocky Mountain Regional Contest | `rmrc` | [Open.Kattis](https://open.kattis.com/problem-sources/Rocky%20Mountain%20Regional%20Programming%20Contest%202025) |
| Southwestern Europe Regional Contest (SWERC) 2009 | Southwestern Europe Regional Contest | `swerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Southwestern%20Europe%20Regional%20Contest%20%28SWERC%29%202009) |
| Southwestern Europe Regional Contest (SWERC) 2010 | Southwestern Europe Regional Contest | `swerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Southwestern%20Europe%20Regional%20Contest%20%28SWERC%29%202010) |
| Southwestern Europe Regional Contest (SWERC) 2011 | Southwestern Europe Regional Contest | `swerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Southwestern%20Europe%20Regional%20Contest%20%28SWERC%29%202011) |
| Southwestern Europe Regional Contest (SWERC) 2012 | Southwestern Europe Regional Contest | `swerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Southwestern%20Europe%20Regional%20Contest%20%28SWERC%29%202012) |
| Southwestern Europe Regional Contest (SWERC) 2013 | Southwestern Europe Regional Contest | `swerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Southwestern%20Europe%20Regional%20Contest%20%28SWERC%29%202013) |
| Southwestern Europe Regional Contest (SWERC) 2014 | Southwestern Europe Regional Contest | `swerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Southwestern%20Europe%20Regional%20Contest%20%28SWERC%29%202014) |
| Southwestern Europe Regional Contest (SWERC) 2015 | Southwestern Europe Regional Contest | `swerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Southwestern%20Europe%20Regional%20Contest%20%28SWERC%29%202015) |
| Southwestern Europe Regional Contest (SWERC) 2016 | Southwestern Europe Regional Contest | `swerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Southwestern%20Europe%20Regional%20Contest%20%28SWERC%29%202016) |
| Southwestern Europe Regional Contest (SWERC) 2017 | Southwestern Europe Regional Contest | `swerc` | [Open.Kattis](https://open.kattis.com/problem-sources/Southwestern%20Europe%20Regional%20Contest%20%28SWERC%29%202017) |
| United Kingdom and Ireland Programming Contest (UKIEPC) 2015 | United Kingdom & Ireland Evening Programming Contest | `ukiepc` | [Open.Kattis](https://open.kattis.com/problem-sources/United%20Kingdom%20and%20Ireland%20Programming%20Contest%20%28UKIEPC%29%202015) |
| United Kingdom and Ireland Programming Contest (UKIEPC) 2016 | United Kingdom & Ireland Evening Programming Contest | `ukiepc` | [Open.Kattis](https://open.kattis.com/problem-sources/United%20Kingdom%20and%20Ireland%20Programming%20Contest%20%28UKIEPC%29%202016) |
| United Kingdom and Ireland Programming Contest (UKIEPC) 2017 | United Kingdom & Ireland Evening Programming Contest | `ukiepc` | [Open.Kattis](https://open.kattis.com/problem-sources/United%20Kingdom%20and%20Ireland%20Programming%20Contest%20%28UKIEPC%29%202017) |
| United Kingdom and Ireland Programming Contest (UKIEPC) 2018 | United Kingdom & Ireland Evening Programming Contest | `ukiepc` | [Open.Kattis](https://open.kattis.com/problem-sources/United%20Kingdom%20and%20Ireland%20Programming%20Contest%20%28UKIEPC%29%202018) |
| United Kingdom and Ireland Programming Contest (UKIEPC) 2019 | United Kingdom & Ireland Evening Programming Contest | `ukiepc` | [Open.Kattis](https://open.kattis.com/problem-sources/United%20Kingdom%20and%20Ireland%20Programming%20Contest%20%28UKIEPC%29%202019) |
| United Kingdom and Ireland Programming Contest (UKIEPC) 2020 | United Kingdom & Ireland Evening Programming Contest | `ukiepc` | [Open.Kattis](https://open.kattis.com/problem-sources/United%20Kingdom%20and%20Ireland%20Programming%20Contest%20%28UKIEPC%29%202020) |
| United Kingdom and Ireland Programming Contest (UKIEPC) 2023 | United Kingdom & Ireland Evening Programming Contest | `ukiepc` | [Open.Kattis](https://open.kattis.com/problem-sources/United%20Kingdom%20and%20Ireland%20Programming%20Contest%20%28UKIEPC%29%202023) |
| United Kingdom and Ireland Programming Contest (UKIEPC) 2024 | United Kingdom & Ireland Evening Programming Contest | `ukiepc` | [Open.Kattis](https://open.kattis.com/problem-sources/United%20Kingdom%20and%20Ireland%20Programming%20Contest%20%28UKIEPC%29%202024) |
## ❌ Unable to Align Kattis Problem Sources
The following Kattis problem sources do not correspond to any of our tracked active ICPC contests (representing national olympiads, school programming classes, corporate contests, etc.):
* [2014 Virginia Tech High School Programming Contest](https://open.kattis.com/problem-sources/2014%20Virginia%20Tech%20High%20School%20Programming%20Contest)
* [2015 ACM ICPC Singapore Regional](https://open.kattis.com/problem-sources/2015%20ACM%20ICPC%20Singapore%20Regional)
* [2015 Virginia Tech High School Programming Contest](https://open.kattis.com/problem-sources/2015%20Virginia%20Tech%20High%20School%20Programming%20Contest)
* [2016 Virginia Tech High School Programming Contest](https://open.kattis.com/problem-sources/2016%20Virginia%20Tech%20High%20School%20Programming%20Contest)
* [2017 Virginia Tech High School Programming Contest](https://open.kattis.com/problem-sources/2017%20Virginia%20Tech%20High%20School%20Programming%20Contest)
* [2018 ICPC Asia Singapore Regional](https://open.kattis.com/problem-sources/2018%20ICPC%20Asia%20Singapore%20Regional)
* [2018 Virginia Tech High School Programming Contest](https://open.kattis.com/problem-sources/2018%20Virginia%20Tech%20High%20School%20Programming%20Contest)
* [2019 UT Invitational Programming Contest](https://open.kattis.com/problem-sources/2019%20UT%20Invitational%20Programming%20Contest)
* [2019 Virginia Tech High School Programming Contest](https://open.kattis.com/problem-sources/2019%20Virginia%20Tech%20High%20School%20Programming%20Contest)
* [2019 Virginia Tech High School Programming Contest (Practice)](https://open.kattis.com/problem-sources/2019%20Virginia%20Tech%20High%20School%20Programming%20Contest%20%28Practice%29)
* [2020 Virginia Tech High School Programming Contest](https://open.kattis.com/problem-sources/2020%20Virginia%20Tech%20High%20School%20Programming%20Contest)
* [2020 Virginia Tech High School Programming Contest (Practice)](https://open.kattis.com/problem-sources/2020%20Virginia%20Tech%20High%20School%20Programming%20Contest%20%28Practice%29)
* [2021 Atlantic Canadian Programming Competition](https://open.kattis.com/problem-sources/2021%20Atlantic%20Canadian%20Programming%20Competition)
* [2021 Virginia Tech High School Programming Contest](https://open.kattis.com/problem-sources/2021%20Virginia%20Tech%20High%20School%20Programming%20Contest)
* [2021 Virginia Tech High School Programming Contest (Practice)](https://open.kattis.com/problem-sources/2021%20Virginia%20Tech%20High%20School%20Programming%20Contest%20%28Practice%29)
* [2022 Atlantic Canadian Programming Competition](https://open.kattis.com/problem-sources/2022%20Atlantic%20Canadian%20Programming%20Competition)
* [2023 Atlantic Canadian Programming Competition](https://open.kattis.com/problem-sources/2023%20Atlantic%20Canadian%20Programming%20Competition)
* [2023 Virginia Tech High School Programming Contest](https://open.kattis.com/problem-sources/2023%20Virginia%20Tech%20High%20School%20Programming%20Contest)
* [2024 Atlantic Canadian Programming Competition](https://open.kattis.com/problem-sources/2024%20Atlantic%20Canadian%20Programming%20Competition)
* [2024 Virginia Tech High School Programming Contest](https://open.kattis.com/problem-sources/2024%20Virginia%20Tech%20High%20School%20Programming%20Contest)
* [2025 Atlantic Canadian Programming Competition](https://open.kattis.com/problem-sources/2025%20Atlantic%20Canadian%20Programming%20Competition)
* [2025 Virginia Tech High School Programming Contest](https://open.kattis.com/problem-sources/2025%20Virginia%20Tech%20High%20School%20Programming%20Contest)
* [2025 Virginia Tech High School Programming Contest (Practice)](https://open.kattis.com/problem-sources/2025%20Virginia%20Tech%20High%20School%20Programming%20Contest%20%28Practice%29)
* [Accenture Coding Challenge 2022](https://open.kattis.com/problem-sources/Accenture%20Coding%20Challenge%202022)
* [Adapted from KTH CSC Popup 2002 Session 1](https://open.kattis.com/problem-sources/Adapted%20from%20KTH%20CSC%20Popup%202002%20Session%201)
* [Adapted from Nada Open 2004](https://open.kattis.com/problem-sources/Adapted%20from%20Nada%20Open%202004)
* [Adapted from Norwegian/Swedish Championships 2003](https://open.kattis.com/problem-sources/Adapted%20from%20Norwegian/Swedish%20Championships%202003)
* [Adapted from Swedish Championships 2000](https://open.kattis.com/problem-sources/Adapted%20from%20Swedish%20Championships%202000)
* [Alberta Collegiate Programming Contest 2016](https://open.kattis.com/problem-sources/Alberta%20Collegiate%20Programming%20Contest%202016)
* [Alberta Collegiate Programming Contest 2017](https://open.kattis.com/problem-sources/Alberta%20Collegiate%20Programming%20Contest%202017)
* [Alberta Collegiate Programming Contest 2018](https://open.kattis.com/problem-sources/Alberta%20Collegiate%20Programming%20Contest%202018)
* [Alberta Collegiate Programming Contest 2020](https://open.kattis.com/problem-sources/Alberta%20Collegiate%20Programming%20Contest%202020)
* [Alberta Collegiate Programming Contest 2021](https://open.kattis.com/problem-sources/Alberta%20Collegiate%20Programming%20Contest%202021)
* [Alberta Collegiate Programming Contest 2022](https://open.kattis.com/problem-sources/Alberta%20Collegiate%20Programming%20Contest%202022)
* [Alberta Collegiate Programming Contest 2023](https://open.kattis.com/problem-sources/Alberta%20Collegiate%20Programming%20Contest%202023)
* [Alberta Collegiate Programming Contest 2024](https://open.kattis.com/problem-sources/Alberta%20Collegiate%20Programming%20Contest%202024)
* [Algorithm Design, ITU 2019](https://open.kattis.com/problem-sources/Algorithm%20Design%2C%20ITU%202019)
* [BOI 2023](https://open.kattis.com/problem-sources/BOI%202023)
* [BYU High School Programming Contest 2022](https://open.kattis.com/problem-sources/BYU%20High%20School%20Programming%20Contest%202022)
* [BYU High School Programming Contest 2025](https://open.kattis.com/problem-sources/BYU%20High%20School%20Programming%20Contest%202025)
* [BYU High School Programming Contest 2026](https://open.kattis.com/problem-sources/BYU%20High%20School%20Programming%20Contest%202026)
* [BYU Winter Programming Contest 2026](https://open.kattis.com/problem-sources/BYU%20Winter%20Programming%20Contest%202026)
* [Baltic Olympiad in Informatics (BOI) 2026, Day 1](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%20%28BOI%29%202026%2C%20Day%201)
* [Baltic Olympiad in Informatics (BOI) 2026, Day 2](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%20%28BOI%29%202026%2C%20Day%202)
* [Baltic Olympiad in Informatics 2001](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202001)
* [Baltic Olympiad in Informatics 2007](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202007)
* [Baltic Olympiad in Informatics 2007, Day 1](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202007%2C%20Day%201)
* [Baltic Olympiad in Informatics 2009, Day 0](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202009%2C%20Day%200)
* [Baltic Olympiad in Informatics 2009, Day 1](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202009%2C%20Day%201)
* [Baltic Olympiad in Informatics 2013](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202013)
* [Baltic Olympiad in Informatics 2014](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202014)
* [Baltic Olympiad in Informatics 2017, Day 1](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202017%2C%20Day%201)
* [Baltic Olympiad in Informatics 2017, Day 2](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202017%2C%20Day%202)
* [Baltic Olympiad in Informatics 2017, Warmup](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202017%2C%20Warmup)
* [Baltic Olympiad in Informatics 2018, day 1](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202018%2C%20day%201)
* [Baltic Olympiad in Informatics 2018, day 2](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202018%2C%20day%202)
* [Baltic Olympiad in Informatics 2018, practice session](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202018%2C%20practice%20session)
* [Baltic Olympiad in Informatics 2024, Day 0](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202024%2C%20Day%200)
* [Baltic Olympiad in Informatics 2024, Day 1](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202024%2C%20Day%201)
* [Baltic Olympiad in Informatics 2024, Day 2](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202024%2C%20Day%202)
* [Baltic Olympiad in Informatics 2025](https://open.kattis.com/problem-sources/Baltic%20Olympiad%20in%20Informatics%202025)
* [Baylor Competitive Learning course](https://open.kattis.com/problem-sources/Baylor%20Competitive%20Learning%20course)
* [Bergen Open 2018](https://open.kattis.com/problem-sources/Bergen%20Open%202018)
* [Bergen Open 2019](https://open.kattis.com/problem-sources/Bergen%20Open%202019)
* [Bergen Open 2021](https://open.kattis.com/problem-sources/Bergen%20Open%202021)
* [CS@Mines High School Programming Competition 2018](https://open.kattis.com/problem-sources/CS%40Mines%20High%20School%20Programming%20Competition%202018)
* [CS@Mines High School Programming Competition 2019](https://open.kattis.com/problem-sources/CS%40Mines%20High%20School%20Programming%20Competition%202019)
* [CS@Mines High School Programming Competition 2020](https://open.kattis.com/problem-sources/CS%40Mines%20High%20School%20Programming%20Competition%202020)
* [CS@Mines High School Programming Competition 2021](https://open.kattis.com/problem-sources/CS%40Mines%20High%20School%20Programming%20Competition%202021)
* [CS@Mines High School Programming Competition 2022](https://open.kattis.com/problem-sources/CS%40Mines%20High%20School%20Programming%20Competition%202022)
* [CS@Mines High School Programming Competition 2023](https://open.kattis.com/problem-sources/CS%40Mines%20High%20School%20Programming%20Competition%202023)
* [CS@Mines High School Programming Competition 2024](https://open.kattis.com/problem-sources/CS%40Mines%20High%20School%20Programming%20Competition%202024)
* [CS@Mines High School Programming Competition 2025](https://open.kattis.com/problem-sources/CS%40Mines%20High%20School%20Programming%20Competition%202025)
* [Calgary Collegiate Programming Contest 2017](https://open.kattis.com/problem-sources/Calgary%20Collegiate%20Programming%20Contest%202017)
* [Calgary Collegiate Programming Contest 2018](https://open.kattis.com/problem-sources/Calgary%20Collegiate%20Programming%20Contest%202018)
* [Calgary Collegiate Programming Contest 2019](https://open.kattis.com/problem-sources/Calgary%20Collegiate%20Programming%20Contest%202019)
* [Calgary Collegiate Programming Contest 2020](https://open.kattis.com/problem-sources/Calgary%20Collegiate%20Programming%20Contest%202020)
* [Calgary Collegiate Programming Contest 2021](https://open.kattis.com/problem-sources/Calgary%20Collegiate%20Programming%20Contest%202021)
* [Calgary Collegiate Programming Contest 2022](https://open.kattis.com/problem-sources/Calgary%20Collegiate%20Programming%20Contest%202022)
* [Calgary Collegiate Programming Contest 2023](https://open.kattis.com/problem-sources/Calgary%20Collegiate%20Programming%20Contest%202023)
* [Calgary Collegiate Programming Contest 2024](https://open.kattis.com/problem-sources/Calgary%20Collegiate%20Programming%20Contest%202024)
* [Calgary Collegiate Programming Contest 2025](https://open.kattis.com/problem-sources/Calgary%20Collegiate%20Programming%20Contest%202025)
* [Camp Inc](https://open.kattis.com/problem-sources/Camp%20Inc)
* [Canadian Computing Competition 2017](https://open.kattis.com/problem-sources/Canadian%20Computing%20Competition%202017)
* [Chalmers Challenge 2021](https://open.kattis.com/problem-sources/Chalmers%20Challenge%202021)
* [Chalmers Challenge 2022](https://open.kattis.com/problem-sources/Chalmers%20Challenge%202022)
* [Chalmers Challenge 2023](https://open.kattis.com/problem-sources/Chalmers%20Challenge%202023)
* [Chalmers Challenge 2024](https://open.kattis.com/problem-sources/Chalmers%20Challenge%202024)
* [Chalmers Challenge 2025](https://open.kattis.com/problem-sources/Chalmers%20Challenge%202025)
* [Chalmers Challenge 2026](https://open.kattis.com/problem-sources/Chalmers%20Challenge%202026)
* [CodePSU 2017 Advanced](https://open.kattis.com/problem-sources/CodePSU%202017%20Advanced)
* [CodePSU 2017 Beginner](https://open.kattis.com/problem-sources/CodePSU%202017%20Beginner)
* [CodePSU 2017 Intermediate](https://open.kattis.com/problem-sources/CodePSU%202017%20Intermediate)
* [CodePSU Spring 2018](https://open.kattis.com/problem-sources/CodePSU%20Spring%202018)
* [CodePSU Spring 2019](https://open.kattis.com/problem-sources/CodePSU%20Spring%202019)
* [CodePSU Spring 2021](https://open.kattis.com/problem-sources/CodePSU%20Spring%202021)
* [CodeSprint LA 2021](https://open.kattis.com/problem-sources/CodeSprint%20LA%202021)
* [CodeSprint LA 2022](https://open.kattis.com/problem-sources/CodeSprint%20LA%202022)
* [CodeSprint LA 2023](https://open.kattis.com/problem-sources/CodeSprint%20LA%202023)
* [CodeSprint LA 2023 Beginner](https://open.kattis.com/problem-sources/CodeSprint%20LA%202023%20Beginner)
* [CodeSprint LA 2024](https://open.kattis.com/problem-sources/CodeSprint%20LA%202024)
* [CodeSprint LA 2025](https://open.kattis.com/problem-sources/CodeSprint%20LA%202025)
* [CodeSprint LA 2026](https://open.kattis.com/problem-sources/CodeSprint%20LA%202026)
* [CodeSprintLA 2020 (UCLA ACM-ICPC)](https://open.kattis.com/problem-sources/CodeSprintLA%202020%20%28UCLA%20ACM-ICPC%29)
* [Coding Cup @ Google 2019](https://open.kattis.com/problem-sources/Coding%20Cup%20%40%20Google%202019)
* [Compete McGill](https://open.kattis.com/problem-sources/Compete%20McGill)
* [Consortium for Computing Sciences in Colleges Mid-South Programming Contest 2018](https://open.kattis.com/problem-sources/Consortium%20for%20Computing%20Sciences%20in%20Colleges%20Mid-South%20Programming%20Contest%202018)
* [Consortium for Computing Sciences in Colleges Mid-South Programming Contest 2019](https://open.kattis.com/problem-sources/Consortium%20for%20Computing%20Sciences%20in%20Colleges%20Mid-South%20Programming%20Contest%202019)
* [Consortium for Computing Sciences in Colleges Mid-South Programming Contest 2020](https://open.kattis.com/problem-sources/Consortium%20for%20Computing%20Sciences%20in%20Colleges%20Mid-South%20Programming%20Contest%202020)
* [Cornell University High School Programming Contest 2019](https://open.kattis.com/problem-sources/Cornell%20University%20High%20School%20Programming%20Contest%202019)
* [Croatian Olympiad in Informatics 2014](https://open.kattis.com/problem-sources/Croatian%20Olympiad%20in%20Informatics%202014)
* [Croatian Open Competition in Informatics 2006/2007, contest #1](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202006/2007%2C%20contest%20%231)
* [Croatian Open Competition in Informatics 2006/2007, contest #2](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202006/2007%2C%20contest%20%232)
* [Croatian Open Competition in Informatics 2006/2007, contest #3](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202006/2007%2C%20contest%20%233)
* [Croatian Open Competition in Informatics 2006/2007, contest #4](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202006/2007%2C%20contest%20%234)
* [Croatian Open Competition in Informatics 2006/2007, contest #5](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202006/2007%2C%20contest%20%235)
* [Croatian Open Competition in Informatics 2006/2007, contest #6](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202006/2007%2C%20contest%20%236)
* [Croatian Open Competition in Informatics 2007/2008, contest #1](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202007/2008%2C%20contest%20%231)
* [Croatian Open Competition in Informatics 2007/2008, contest #2](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202007/2008%2C%20contest%20%232)
* [Croatian Open Competition in Informatics 2007/2008, contest #3](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202007/2008%2C%20contest%20%233)
* [Croatian Open Competition in Informatics 2007/2008, contest #4](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202007/2008%2C%20contest%20%234)
* [Croatian Open Competition in Informatics 2007/2008, contest #5](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202007/2008%2C%20contest%20%235)
* [Croatian Open Competition in Informatics 2007/2008, contest #6](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202007/2008%2C%20contest%20%236)
* [Croatian Open Competition in Informatics 2008/2009, contest #1](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202008/2009%2C%20contest%20%231)
* [Croatian Open Competition in Informatics 2008/2009, contest #2](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202008/2009%2C%20contest%20%232)
* [Croatian Open Competition in Informatics 2008/2009, contest #3](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202008/2009%2C%20contest%20%233)
* [Croatian Open Competition in Informatics 2008/2009, contest #4](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202008/2009%2C%20contest%20%234)
* [Croatian Open Competition in Informatics 2008/2009, contest #6](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202008/2009%2C%20contest%20%236)
* [Croatian Open Competition in Informatics 2009/2010, contest #1](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202009/2010%2C%20contest%20%231)
* [Croatian Open Competition in Informatics 2009/2010, contest #2](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202009/2010%2C%20contest%20%232)
* [Croatian Open Competition in Informatics 2009/2010, contest #3](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202009/2010%2C%20contest%20%233)
* [Croatian Open Competition in Informatics 2009/2010, contest #4](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202009/2010%2C%20contest%20%234)
* [Croatian Open Competition in Informatics 2009/2010, contest #5](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202009/2010%2C%20contest%20%235)
* [Croatian Open Competition in Informatics 2009/2010, contest #6](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202009/2010%2C%20contest%20%236)
* [Croatian Open Competition in Informatics 2009/2010, contest #7](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202009/2010%2C%20contest%20%237)
* [Croatian Open Competition in Informatics 2010/2011, contest #1](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202010/2011%2C%20contest%20%231)
* [Croatian Open Competition in Informatics 2010/2011, contest #2](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202010/2011%2C%20contest%20%232)
* [Croatian Open Competition in Informatics 2010/2011, contest #3](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202010/2011%2C%20contest%20%233)
* [Croatian Open Competition in Informatics 2010/2011, contest #4](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202010/2011%2C%20contest%20%234)
* [Croatian Open Competition in Informatics 2010/2011, contest #5](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202010/2011%2C%20contest%20%235)
* [Croatian Open Competition in Informatics 2011/2012, contest #2](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202011/2012%2C%20contest%20%232)
* [Croatian Open Competition in Informatics 2011/2012, contest #5](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202011/2012%2C%20contest%20%235)
* [Croatian Open Competition in Informatics 2011/2012, contest #6](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202011/2012%2C%20contest%20%236)
* [Croatian Open Competition in Informatics 2012/2013, contest #3](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202012/2013%2C%20contest%20%233)
* [Croatian Open Competition in Informatics 2012/2013, contest #6](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202012/2013%2C%20contest%20%236)
* [Croatian Open Competition in Informatics 2013/2014, contest #2](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202013/2014%2C%20contest%20%232)
* [Croatian Open Competition in Informatics 2013/2014, contest #3](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202013/2014%2C%20contest%20%233)
* [Croatian Open Competition in Informatics 2013/2014, contest #4](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202013/2014%2C%20contest%20%234)
* [Croatian Open Competition in Informatics 2013/2014, contest #5](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202013/2014%2C%20contest%20%235)
* [Croatian Open Competition in Informatics 2013/2014, contest #6](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202013/2014%2C%20contest%20%236)
* [Croatian Open Competition in Informatics 2013/2014, contest 1](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202013/2014%2C%20contest%201)
* [Croatian Open Competition in Informatics 2013/2014, contest 4](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202013/2014%2C%20contest%204)
* [Croatian Open Competition in Informatics 2014/2015, contest #1](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202014/2015%2C%20contest%20%231)
* [Croatian Open Competition in Informatics 2014/2015, contest #2](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202014/2015%2C%20contest%20%232)
* [Croatian Open Competition in Informatics 2014/2015, contest #3](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202014/2015%2C%20contest%20%233)
* [Croatian Open Competition in Informatics 2014/2015, contest #4](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202014/2015%2C%20contest%20%234)
* [Croatian Open Competition in Informatics 2014/2015, contest #5](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202014/2015%2C%20contest%20%235)
* [Croatian Open Competition in Informatics 2014/2015, contest #6](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202014/2015%2C%20contest%20%236)
* [Croatian Open Competition in Informatics 2014/2015, contest #7](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202014/2015%2C%20contest%20%237)
* [Croatian Open Competition in Informatics 2015/2016, contest #1](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202015/2016%2C%20contest%20%231)
* [Croatian Open Competition in Informatics 2015/2016, contest #2](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202015/2016%2C%20contest%20%232)
* [Croatian Open Competition in Informatics 2015/2016, contest #3](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202015/2016%2C%20contest%20%233)
* [Croatian Open Competition in Informatics 2015/2016, contest #4](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202015/2016%2C%20contest%20%234)
* [Croatian Open Competition in Informatics 2015/2016, contest #5](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202015/2016%2C%20contest%20%235)
* [Croatian Open Competition in Informatics 2015/2016, contest #6](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202015/2016%2C%20contest%20%236)
* [Croatian Open Competition in Informatics 2015/2016, contest #7](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202015/2016%2C%20contest%20%237)
* [Croatian Open Competition in Informatics 2016/2017, contest #1](https://open.kattis.com/problem-sources/Croatian%20Open%20Competition%20in%20Informatics%202016/2017%2C%20contest%20%231)
* [Croatian Regional Competition in Informatics 2007](https://open.kattis.com/problem-sources/Croatian%20Regional%20Competition%20in%20Informatics%202007)
* [Croatian Regional Competition in Informatics 2008](https://open.kattis.com/problem-sources/Croatian%20Regional%20Competition%20in%20Informatics%202008)
* [Croatian Regional Contest 2008/2009](https://open.kattis.com/problem-sources/Croatian%20Regional%20Contest%202008/2009)
* [Czech-Polish-Slovak Programming Camp 2008](https://open.kattis.com/problem-sources/Czech-Polish-Slovak%20Programming%20Camp%202008)
* [Czech-Polish-Slovak Programming Camp 2009](https://open.kattis.com/problem-sources/Czech-Polish-Slovak%20Programming%20Camp%202009)
* [D-POP](https://open.kattis.com/problem-sources/D-POP)
* [D-Pop 2021](https://open.kattis.com/problem-sources/D-Pop%202021)
* [D-Pop 2022](https://open.kattis.com/problem-sources/D-Pop%202022)
* [D-Pop 2024](https://open.kattis.com/problem-sources/D-Pop%202024)
* [Doris 2023 deltävling 1](https://open.kattis.com/problem-sources/Doris%202023%20delt%C3%A4vling%201)
* [Doris 2023 deltävling 2](https://open.kattis.com/problem-sources/Doris%202023%20delt%C3%A4vling%202)
* [Doris 2023 deltävling 3](https://open.kattis.com/problem-sources/Doris%202023%20delt%C3%A4vling%203)
* [Doris 2024 deltävling 1](https://open.kattis.com/problem-sources/Doris%202024%20delt%C3%A4vling%201)
* [Doris 2024 deltävling 2](https://open.kattis.com/problem-sources/Doris%202024%20delt%C3%A4vling%202)
* [E-402-STFO 2024 Module 1](https://open.kattis.com/problem-sources/E-402-STFO%202024%20Module%201)
* [E-402-STFO 2024 Module 2](https://open.kattis.com/problem-sources/E-402-STFO%202024%20Module%202)
* [E-402-STFO 2024 Module 3](https://open.kattis.com/problem-sources/E-402-STFO%202024%20Module%203)
* [E-402-STFO 2024 Module 4](https://open.kattis.com/problem-sources/E-402-STFO%202024%20Module%204)
* [E-402-STFO 2024 Module H](https://open.kattis.com/problem-sources/E-402-STFO%202024%20Module%20H)
* [E-402-STFO 2024 Module N](https://open.kattis.com/problem-sources/E-402-STFO%202024%20Module%20N)
* [E-402-STFO 2024 Module P](https://open.kattis.com/problem-sources/E-402-STFO%202024%20Module%20P)
* [E-402-STFO 2025 Module 3](https://open.kattis.com/problem-sources/E-402-STFO%202025%20Module%203)
* [EGOI 2024 kvaltävling 2](https://open.kattis.com/problem-sources/EGOI%202024%20kvalt%C3%A4vling%202)
* [EGOI Kvaltävling 1 2026](https://open.kattis.com/problem-sources/EGOI%20Kvalt%C3%A4vling%201%202026)
* [Ericsson Programming Challenge 2017](https://open.kattis.com/problem-sources/Ericsson%20Programming%20Challenge%202017)
* [EuroPython 2011](https://open.kattis.com/problem-sources/EuroPython%202011)
* [Europe Women's Programming Contest (EWPC) 2026 Finals](https://open.kattis.com/problem-sources/Europe%20Women%27s%20Programming%20Contest%20%28EWPC%29%202026%20Finals)
* [Europe Women's Programming Contest (EWPC) 2026 Qualifier](https://open.kattis.com/problem-sources/Europe%20Women%27s%20Programming%20Contest%20%28EWPC%29%202026%20Qualifier)
* [European Girls' Olympiad in Informatics 2023](https://open.kattis.com/problem-sources/European%20Girls%27%20Olympiad%20in%20Informatics%202023)
* [European Girls' Olympiad in Informatics 2024](https://open.kattis.com/problem-sources/European%20Girls%27%20Olympiad%20in%20Informatics%202024)
* [European Girls' Olympiad in Informatics 2025](https://open.kattis.com/problem-sources/European%20Girls%27%20Olympiad%20in%20Informatics%202025)
* [Fall 2019 UT Invitational Programming Contest](https://open.kattis.com/problem-sources/Fall%202019%20UT%20Invitational%20Programming%20Contest)
* [Forritunarkeppni Framhaldsskólanna 2016](https://open.kattis.com/problem-sources/Forritunarkeppni%20Framhaldssk%C3%B3lanna%202016)
* [Forritunarkeppni Framhaldsskólanna 2017](https://open.kattis.com/problem-sources/Forritunarkeppni%20Framhaldssk%C3%B3lanna%202017)
* [Forritunarkeppni Framhaldsskólanna 2018](https://open.kattis.com/problem-sources/Forritunarkeppni%20Framhaldssk%C3%B3lanna%202018)
* [Forritunarkeppni Framhaldsskólanna 2019](https://open.kattis.com/problem-sources/Forritunarkeppni%20Framhaldssk%C3%B3lanna%202019)
* [Forritunarkeppni Framhaldsskólanna 2020](https://open.kattis.com/problem-sources/Forritunarkeppni%20Framhaldssk%C3%B3lanna%202020)
* [Forritunarkeppni Framhaldsskólanna 2021](https://open.kattis.com/problem-sources/Forritunarkeppni%20Framhaldssk%C3%B3lanna%202021)
* [Forritunarkeppni Framhaldsskólanna 2022](https://open.kattis.com/problem-sources/Forritunarkeppni%20Framhaldssk%C3%B3lanna%202022)
* [Forritunarkeppni Framhaldsskólanna 2023](https://open.kattis.com/problem-sources/Forritunarkeppni%20Framhaldssk%C3%B3lanna%202023)
* [Forritunarkeppni Framhaldsskólanna 2024](https://open.kattis.com/problem-sources/Forritunarkeppni%20Framhaldssk%C3%B3lanna%202024)
* [Forritunarkeppni Framhaldsskólanna 2025](https://open.kattis.com/problem-sources/Forritunarkeppni%20Framhaldssk%C3%B3lanna%202025)
* [Forritunarkeppni Framhaldsskólanna 2026](https://open.kattis.com/problem-sources/Forritunarkeppni%20Framhaldssk%C3%B3lanna%202026)
* [Forritunarkeppni Háskóla Íslands 2019](https://open.kattis.com/problem-sources/Forritunarkeppni%20H%C3%A1sk%C3%B3la%20%C3%8Dslands%202019)
* [Forritunarkeppni Háskóla Íslands 2020](https://open.kattis.com/problem-sources/Forritunarkeppni%20H%C3%A1sk%C3%B3la%20%C3%8Dslands%202020)
* [Forritunarkeppni Háskóla Íslands 2021](https://open.kattis.com/problem-sources/Forritunarkeppni%20H%C3%A1sk%C3%B3la%20%C3%8Dslands%202021)
* [Forritunarkeppni Háskóla Íslands 2022](https://open.kattis.com/problem-sources/Forritunarkeppni%20H%C3%A1sk%C3%B3la%20%C3%8Dslands%202022)
* [Forritunarkeppni Háskólanna á Íslandi 2023](https://open.kattis.com/problem-sources/Forritunarkeppni%20H%C3%A1sk%C3%B3lanna%20%C3%A1%20%C3%8Dslandi%202023)
* [Forritunarkeppni Háskólanna á Íslandi 2024](https://open.kattis.com/problem-sources/Forritunarkeppni%20H%C3%A1sk%C3%B3lanna%20%C3%A1%20%C3%8Dslandi%202024)
* [Forritunarkeppni Háskólanna á Íslandi 2025](https://open.kattis.com/problem-sources/Forritunarkeppni%20H%C3%A1sk%C3%B3lanna%20%C3%A1%20%C3%8Dslandi%202025)
* [Forritunarkeppni Háskólanna á Íslandi 2026](https://open.kattis.com/problem-sources/Forritunarkeppni%20H%C3%A1sk%C3%B3lanna%20%C3%A1%20%C3%8Dslandi%202026)
* [Freshmen Programming Contests (FPC) 2023](https://open.kattis.com/problem-sources/Freshmen%20Programming%20Contests%20%28FPC%29%202023)
* [Freshmen Programming Contests (FPC) 2024](https://open.kattis.com/problem-sources/Freshmen%20Programming%20Contests%20%28FPC%29%202024)
* [Freshmen Programming Contests (FPC) 2025](https://open.kattis.com/problem-sources/Freshmen%20Programming%20Contests%20%28FPC%29%202025)
* [Freshmen Programming Contests (FPC) 2026](https://open.kattis.com/problem-sources/Freshmen%20Programming%20Contests%20%28FPC%29%202026)
* [Google Code Jam 2008 Beta](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202008%20Beta)
* [Google Code Jam 2008 EMEA Semifinal](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202008%20EMEA%20Semifinal)
* [Google Code Jam 2008 Qualification Round](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202008%20Qualification%20Round)
* [Google Code Jam 2008 Round 1A](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202008%20Round%201A)
* [Google Code Jam 2008 Round 1B](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202008%20Round%201B)
* [Google Code Jam 2008 Round 1C](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202008%20Round%201C)
* [Google Code Jam 2008 Round 2](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202008%20Round%202)
* [Google Code Jam 2008 Round 3](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202008%20Round%203)
* [Google Code Jam 2009 Qualification Round](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202009%20Qualification%20Round)
* [Google Code Jam 2010 Online Competition Africa](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202010%20Online%20Competition%20Africa)
* [Google Code Jam 2010 Qualification Round](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202010%20Qualification%20Round)
* [Google Code Jam 2010 Qualification Round Africa](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202010%20Qualification%20Round%20Africa)
* [Google Code Jam 2011 Online Competition Africa and Arabia](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202011%20Online%20Competition%20Africa%20and%20Arabia)
* [Google Code Jam 2011 Qualification Round Africa and Arabia](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202011%20Qualification%20Round%20Africa%20and%20Arabia)
* [Google Code Jam 2012](https://open.kattis.com/problem-sources/Google%20Code%20Jam%202012)
* [Google Code Jam Practice Contest](https://open.kattis.com/problem-sources/Google%20Code%20Jam%20Practice%20Contest)
* [Google Code Jam Practice Problems](https://open.kattis.com/problem-sources/Google%20Code%20Jam%20Practice%20Problems)
* [Hendrix College Programming Contest 2024](https://open.kattis.com/problem-sources/Hendrix%20College%20Programming%20Contest%202024)
* [Hendrix College Programming Contest 2025](https://open.kattis.com/problem-sources/Hendrix%20College%20Programming%20Contest%202025)
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* [ITMO Internet Olympiads 12.11.2011](https://open.kattis.com/problem-sources/ITMO%20Internet%20Olympiads%2012.11.2011)
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* [Icelandic High School Competition 2014](https://open.kattis.com/problem-sources/Icelandic%20High%20School%20Competition%202014)
* [International Collegiate Programming Contest (ACM-ICPC) Dress Rehearsal 2012](https://open.kattis.com/problem-sources/International%20Collegiate%20Programming%20Contest%20%28ACM-ICPC%29%20Dress%20Rehearsal%202012)
* [International Collegiate Programming Contest (ACM-ICPC) Dress Rehearsal 2015](https://open.kattis.com/problem-sources/International%20Collegiate%20Programming%20Contest%20%28ACM-ICPC%29%20Dress%20Rehearsal%202015)
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* [JobAgent Challenge 2021](https://open.kattis.com/problem-sources/JobAgent%20Challenge%202021)
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* [KTH Challenge 2017](https://open.kattis.com/problem-sources/KTH%20Challenge%202017)
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* [Nordic Olympiad in Informatics 2026](https://open.kattis.com/problem-sources/Nordic%20Olympiad%20in%20Informatics%202026)
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* [Nova Challenge 2018](https://open.kattis.com/problem-sources/Nova%20Challenge%202018)
* [Oxford Programming Contest 2007](https://open.kattis.com/problem-sources/Oxford%20Programming%20Contest%202007)
* [Polish Informatics Olympiad 2022](https://open.kattis.com/problem-sources/Polish%20Informatics%20Olympiad%202022)
* [Popup 2015 Session 1](https://open.kattis.com/problem-sources/Popup%202015%20Session%201)
* [Principles of Algorithmic Problem Solving](https://open.kattis.com/problem-sources/Principles%20of%20Algorithmic%20Problem%20Solving)
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* [Programmeringsolympiadens KATT 2020](https://open.kattis.com/problem-sources/Programmeringsolympiadens%20KATT%202020)
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* [Programmeringsolympiadens distriktsmästerskap 2016](https://open.kattis.com/problem-sources/Programmeringsolympiadens%20distriktsm%C3%A4sterskap%202016)
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* [Programmeringsolympiadens lägertävling 2026 - dag 1](https://open.kattis.com/problem-sources/Programmeringsolympiadens%20l%C3%A4gert%C3%A4vling%202026%20-%20dag%201)
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* [Programming Battle, contest Beta](https://open.kattis.com/problem-sources/Programming%20Battle%2C%20contest%20Beta)
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* [Rujia Liu's Present 3: A datastructure contest celebrating the 100th anniversary of Tsinghua University](https://open.kattis.com/problem-sources/Rujia%20Liu%27s%20Present%203%3A%20A%20datastructure%20contest%20celebrating%20the%20100th%20anniversary%20of%20Tsinghua%20University)
* [Rutgers Spring Contest](https://open.kattis.com/problem-sources/Rutgers%20Spring%20Contest)
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* [SPb School Team Olympiad 2010](https://open.kattis.com/problem-sources/SPb%20School%20Team%20Olympiad%202010)
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* [SPb School Team Olympiad 2018](https://open.kattis.com/problem-sources/SPb%20School%20Team%20Olympiad%202018)
* [Sjúkrapróf í TÖL607G 2024](https://open.kattis.com/problem-sources/Sj%C3%BAkrapr%C3%B3f%20%C3%AD%20T%C3%96L607G%202024)
* [Skot og Skil 2026](https://open.kattis.com/problem-sources/Skot%20og%20Skil%202026)
* [Slovak Olympiad in Informatics Training Camp](https://open.kattis.com/problem-sources/Slovak%20Olympiad%20in%20Informatics%20Training%20Camp)
* [Spotify Challenge 2010](https://open.kattis.com/problem-sources/Spotify%20Challenge%202010)
* [Spotify Challenge 2011](https://open.kattis.com/problem-sources/Spotify%20Challenge%202011)
* [Spotify Code Quest 2012](https://open.kattis.com/problem-sources/Spotify%20Code%20Quest%202012)
* [Spring 2020 UT Invitational Programming Contest](https://open.kattis.com/problem-sources/Spring%202020%20UT%20Invitational%20Programming%20Contest)
* [Stanford Local Programming Contest 2026](https://open.kattis.com/problem-sources/Stanford%20Local%20Programming%20Contest%202026)
* [Swedish Championships 2000](https://open.kattis.com/problem-sources/Swedish%20Championships%202000)
* [Swedish Championships 2001](https://open.kattis.com/problem-sources/Swedish%20Championships%202001)
* [Swedish Coding Cup Finals 2018](https://open.kattis.com/problem-sources/Swedish%20Coding%20Cup%20Finals%202018)
* [Swedish Coding Cup Finals 2019](https://open.kattis.com/problem-sources/Swedish%20Coding%20Cup%20Finals%202019)
* [Swedish Coding Cup Finals 2021](https://open.kattis.com/problem-sources/Swedish%20Coding%20Cup%20Finals%202021)
* [Swedish Coding Cup Finals 2022](https://open.kattis.com/problem-sources/Swedish%20Coding%20Cup%20Finals%202022)
* [Swedish Coding Cup Finals 2026](https://open.kattis.com/problem-sources/Swedish%20Coding%20Cup%20Finals%202026)
* [Swedish ICPC Qualifier 2009](https://open.kattis.com/problem-sources/Swedish%20ICPC%20Qualifier%202009)
* [T-111-Programming](https://open.kattis.com/problem-sources/T-111-Programming)
* [T-301-REIR Algorithms](https://open.kattis.com/problem-sources/T-301-REIR%20Algorithms)
* [T-403-FORC Programming in C++](https://open.kattis.com/problem-sources/T-403-FORC%20Programming%20in%20C%2B%2B)
* [T-513-Cryptography and Number Theory](https://open.kattis.com/problem-sources/T-513-Cryptography%20and%20Number%20Theory)
* [Texas Regional Programming Contest 1974](https://open.kattis.com/problem-sources/Texas%20Regional%20Programming%20Contest%201974)
* [The 14th Zhejiang Provincial Collegiate Programming Contest](https://open.kattis.com/problem-sources/The%2014th%20Zhejiang%20Provincial%20Collegiate%20Programming%20Contest)
* [The 2016 ACM - ICPC Asia Nha Trang Regional Contest](https://open.kattis.com/problem-sources/The%202016%20ACM%20-%20ICPC%20Asia%20Nha%20Trang%20Regional%20Contest)
* [The 2017 ACM - ICPC Asia Ho Chi Minh City Regional Contest](https://open.kattis.com/problem-sources/The%202017%20ACM%20-%20ICPC%20Asia%20Ho%20Chi%20Minh%20City%20Regional%20Contest)
* [The 2017 ACM - ICPC Vietnam National Programming Contest](https://open.kattis.com/problem-sources/The%202017%20ACM%20-%20ICPC%20Vietnam%20National%20Programming%20Contest)
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* [The 2018 ICPC Asia Hanoi Regional Contest](https://open.kattis.com/problem-sources/The%202018%20ICPC%20Asia%20Hanoi%20Regional%20Contest)
* [The 2018 ICPC Vietnam National Programming Contest](https://open.kattis.com/problem-sources/The%202018%20ICPC%20Vietnam%20National%20Programming%20Contest)
* [The 2019 ICPC Asia Danang Regional Contest](https://open.kattis.com/problem-sources/The%202019%20ICPC%20Asia%20Danang%20Regional%20Contest)
* [The 2019 ICPC Vietnam National Contest](https://open.kattis.com/problem-sources/The%202019%20ICPC%20Vietnam%20National%20Contest)
* [The 2020 ICPC Asia Can Tho Regional Contest](https://open.kattis.com/problem-sources/The%202020%20ICPC%20Asia%20Can%20Tho%20Regional%20Contest)
* [The 2020 ICPC Vietnam National Contest](https://open.kattis.com/problem-sources/The%202020%20ICPC%20Vietnam%20National%20Contest)
* [The 2nd ProgNova Multi-University Programming Contest (2016)](https://open.kattis.com/problem-sources/The%202nd%20ProgNova%20Multi-University%20Programming%20Contest%20%282016%29)
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* [University of Alberta Programming Contest 2022](https://open.kattis.com/problem-sources/University%20of%20Alberta%20Programming%20Contest%202022)
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* [University of Chicago - Department of Computer Science](https://open.kattis.com/problem-sources/University%20of%20Chicago%20-%20Department%20of%20Computer%20Science)
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* [University of Ulm Local Contest 1997](https://open.kattis.com/problem-sources/University%20of%20Ulm%20Local%20Contest%201997)
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* [VTEX Code Cup](https://open.kattis.com/problem-sources/VTEX%20Code%20Cup)
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* [Waterloo Programming Contest 1997-10-18](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%201997-10-18)
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* [Waterloo Programming Contest 1999-06-19](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%201999-06-19)
* [Waterloo Programming Contest 1999-09-25](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%201999-09-25)
* [Waterloo Programming Contest 1999-10-02](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%201999-10-02)
* [Waterloo Programming Contest 2000-01-29](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202000-01-29)
* [Waterloo Programming Contest 2000-09-23](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202000-09-23)
* [Waterloo Programming Contest 2000-09-30](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202000-09-30)
* [Waterloo Programming Contest 2001-01-27](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202001-01-27)
* [Waterloo Programming Contest 2001-06-02](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202001-06-02)
* [Waterloo Programming Contest 2001-09-22](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202001-09-22)
* [Waterloo Programming Contest 2001-09-29](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202001-09-29)
* [Waterloo Programming Contest 2001-10-20](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202001-10-20)
* [Waterloo Programming Contest 2002-01-26](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202002-01-26)
* [Waterloo Programming Contest 2002-06-01](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202002-06-01)
* [Waterloo Programming Contest 2002-09-21](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202002-09-21)
* [Waterloo Programming Contest 2002-09-28](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202002-09-28)
* [Waterloo Programming Contest 2003-01-25](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202003-01-25)
* [Waterloo Programming Contest 2003-07-05](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202003-07-05)
* [Waterloo Programming Contest 2003-09-20](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202003-09-20)
* [Waterloo Programming Contest 2003-09-27](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202003-09-27)
* [Waterloo Programming Contest 2004-01-31](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202004-01-31)
* [Waterloo Programming Contest 2004-09-19](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202004-09-19)
* [Waterloo Programming Contest 2004-09-25](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202004-09-25)
* [Waterloo Programming Contest 2005-02-05](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202005-02-05)
* [Waterloo Programming Contest 2005-09-17](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202005-09-17)
* [Waterloo Programming Contest 2005-09-24](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202005-09-24)
* [Waterloo Programming Contest 2006-02-25](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202006-02-25)
* [Waterloo Programming Contest 2006-05-27](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202006-05-27)
* [Waterloo Programming Contest 2006-09-24](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202006-09-24)
* [Waterloo Programming Contest 2006-09-30](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202006-09-30)
* [Waterloo Programming Contest 2007-07-14](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202007-07-14)
* [Waterloo Programming Contest 2007-09-23](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202007-09-23)
* [Waterloo Programming Contest 2007-09-29](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202007-09-29)
* [Waterloo Programming Contest 2008-06-15](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202008-06-15)
* [Waterloo Programming Contest 2008-09-27](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202008-09-27)
* [Waterloo Programming Contest 2008-10-04](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202008-10-04)
* [Waterloo Programming Contest 2009-02-08](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202009-02-08)
* [Waterloo Programming Contest 2009-06-13](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202009-06-13)
* [Waterloo Programming Contest 2009-09-27](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202009-09-27)
* [Waterloo Programming Contest 2009-10-03](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202009-10-03)
* [Waterloo Programming Contest 2010-07-10](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202010-07-10)
* [Waterloo Programming Contest 2010-09-26](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202010-09-26)
* [Waterloo Programming Contest 2010-10-02](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202010-10-02)
* [Waterloo Programming Contest 2011-09-24](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202011-09-24)
* [Waterloo Programming Contest 2012-09-16](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202012-09-16)
* [Waterloo Programming Contest 2012-10-13](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202012-10-13)
* [Waterloo Programming Contest 2015-07-18](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202015-07-18)
* [Waterloo Programming Contest 2015-09-27](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202015-09-27)
* [Waterloo Programming Contest 2016-10-01](https://open.kattis.com/problem-sources/Waterloo%20Programming%20Contest%202016-10-01)
* [Waterloo/Alberta Programming Contest 2004-06-12](https://open.kattis.com/problem-sources/Waterloo/Alberta%20Programming%20Contest%202004-06-12)
* [Waterloo/Alberta Programming Contest 2005-06-11](https://open.kattis.com/problem-sources/Waterloo/Alberta%20Programming%20Contest%202005-06-11)
* [Will Code for Drinks 2019/2](https://open.kattis.com/problem-sources/Will%20Code%20for%20Drinks%202019/2)
* [Will Code for Drinks 2021](https://open.kattis.com/problem-sources/Will%20Code%20for%20Drinks%202021)
* [Will Code for Drinks 2022](https://open.kattis.com/problem-sources/Will%20Code%20for%20Drinks%202022)
* [Will Code for Drinks 2023](https://open.kattis.com/problem-sources/Will%20Code%20for%20Drinks%202023)
* [Will Code for Drinks 2024](https://open.kattis.com/problem-sources/Will%20Code%20for%20Drinks%202024)