JOI Open Contest 2015

This is an IOI-like open competition for students at schools for secondary education. The main purpose of this contest is to give an opportunity to Japanese delegations and candidates of delegations for training and practice. But the contest itself is open to everybody. Everybody is welcome to attend JOI Open Contest 2015!

The duration of the contest is 5 hours. The same contests are held twice (Round 1 and Round 2). Contestants can participate in one of Round 1 or Round 2 according to their time zone. After Round 2 finishes, we will open the judging server for one day. Interested contestants can improve and resubmit their solutions by themselves.

Registration will be open before each contest. A link to the registration page will appear on this page about 30 minutes before the beginning of each contest. Contestants can register on the contest site by themselves from the right before the beginning of each contest until the end of it.

No prizes will be given to the contestants.

Contest Information

JOI Open Contest 2015
Contest System
Contest duration
5 hours
The number of tasks
3 tasks
English, Japanese
Round 1
Sunday, June 14, 2015
13:00-18:00 +0900 (JST)
04:00-09:00 (UTC/GMT)
Round 2 (tasks for Round 1 and Round 2 are the same)
Sunday, June 14, 2015
19:00-24:00 +0900 (JST)
10:00-15:00 (UTC/GMT)
Judging Server is open until
Monday, June 15, 2015
23:00 +0900 (JST)
14:00 (UTC/GMT)


Rules that are same as IOI 2015 Rule:

Rules that are not same as IOI 2015 Rule:

Contet Site

The contest is over.


Problem Statements


Test Data


joiopen at