Mid-Atlantic Regional Contest 2002 Problems

Problem description (modified to reflect clarifications issued during contest).

Practice Problem

Judges' Solutions and Test Data

Clarifications issued during contest

Problem E: A Baron Landscape

Q: Does "within 6 days" mean <= 6 or <6.
A: <= 6

Problem B: An Amazing Problem

Q: Is the space outside the maze the letter 'O' or the number 0 (zero)?
A: The space is the letter 'O' not the digit '0'

Problem A: A Simple Question of Chemistry

Q: How do we display a difference of exactly zero? (With regard to the no leading zeros restrictions) 0.00? .00? Some other way?
A: We prefer 0.00, however we have accepted .00

Several problems

Q: Are we supposed to have an endline after "End of Output"?
A: We will accept either way. We prefer a newline.

Judges' Comments

Time limit

This year the time limit was reduced from 2 minutes to 30 seconds. In the past, we have found that for problems where the time limit is an issue, typically a good solution completes in seconds, whereas a bad solution may take hours. Therefore, it was generally obvious within a few seconds whether the solution was valid or not, but judges had to wait for the full two minutes for each submission. This wait caused backlogs in judging these problems. This year we reduced the time limit to reduce these backlogs. The judges' solutions, in both C and Java, for all of the problems solved the test data used during the contest in under two seconds on an 800Mhz P3.

Problem B: An Amazing Problem

This was the most unusual of the problems. A number of teams seemed to have a hard time understanding the concept behind the question, asking clarifications such as "Do we have to find the optimal path?" Obviously an optimal path can't be calculated unless you have a map of the entire maze at the start, which you don't in this problem.

We found that some submissions did not work because they used IO calls that did not flush the output buffer after each line. Because we felt that output buffer flushing was beyond the scope of the programming contest, we modified such submissions to flush their buffer after each line before judging them.

Problem C: Spelling Be

This problem is essentially a test of algorithm efficiency. The dictionary and emails are large enough that simply reading the dictionary into an array and doing linear search on it for each word will take too long. Any reasonably efficient solution to sorting and searching will solve the problem in a second or less. Our Java solution uses a HashSet from the JDK API to achieve constant time storage and lookups. Our C++ solution uses old-fashioned qsort and bsearch from stdlib. A C++ STL solution using vectors and sort could also be used.

Alternatively, a team could have coded up an efficient sort and search on their own. But one of the important skills in a programming contest is recognizing the power of the tools you have at your disposal. For teams that use libraries effectively, this was an easy problem.