Final Report

November 4, 2015

The 2015 ACM ICPC East Central North America Regional Programming Contest (ACM ICPC ECNA RPC) was held on Saturday, October 31, 2015. We had 130 teams from 55 colleges and universities throughout western Pennsylvania, Ohio, Michigan, eastern Ontario, and Indiana (excluding the Greater Chicago Metropolitan Area).

As it was difficult for some teams in the ECNA region to travel to a single site for the contest, the ECNA RPC was held as a distributed contest. There were four contest sites:

The ECNA RPC was successful, although there were two issues of note; those are discussed more fully below. First, some observations:


Problem B Judges' Solutions Incorrect

An appeal was made regarding the interpretation of the procedure described in problem B. In the problem, a rectangle was to be drawn on a screen whose bounds were specified in the input. The appeal claimed that the judges’ solutions allowed the rectangle to be drawn beyond the borders of the screen. While the intent of the judges was to keep the rectangle on-screen, there were four test cases where the rectangle would have to be extended beyond the borders in order to get answers that matched the judges’ output.

It was discovered that both of the judges’ solutions were flawed and neither solution realized that the rectangle extended beyond the screen border.

The four test cases were corrected and all 57 submissions for the problem were reexamined. The results of the examination are summarized below.

A corrected problem was sent to Kattis to provide corrected results.

Of the four submissions rejudged to be accepted, two were by teams that had a later submission that was accepted on the original test data and two were by teams that were not credited with solving the problem.

The changes in standing as a result of rejudging were as follows:

This caused some movement among the top nine teams; Waterloo White and OSU_1 exchanged places, CMU1 moved from ninth place to fifth place, Toronto Blue moved from fifth place to sixth place, CMU3 moved from sixth place to eighth place and Waterloo Red moved from eighth place to ninth place.

Password issue

For increased security, Kattis used two sets of passwords – one for the practice contest and a second set for the actual contest. The second passwords were delivered to the RCD about two hours after the practice contest ended; these were then distributed to the sites.

At the start of the contest, teams at two sites continued to use the first set of passwords and were unable to log in at the start of the contest.

After discussion with the sites and confirmation from Kattis staff, the problem was recognized and the second passwords were distributed. This caused a delay of 12 minutes at one site and somewhat longer at the second site. It should be noted that six of the top ten teams were at delayed sites.

You can view the final standings here.

You can view the problem sets, test data and judges' solutions here.

Special Awards

Congratulations to the following teams on their awards:

Note: Teams are only eligible to win one prize.