JOI Open Contest 2019

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 2019!

The duration of the contest is 5 hours. The same contests are held three times (Round 1, Round 2 and Round 3). Contestants can participate in one of Round 1, Round 2 or Round 3 according to their time zone. After Round 3 finishes, we will open the judging server for one week. 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 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.

The ranking will be public during and after the contest. It includes your username, first name, and last name provided via the registration form.

Contest Information

JOI Open Contest 2019
Contest System
Contest duration
5 hours
The number of tasks
3 tasks
English, Japanese
Round 1
Sunday, July 14, 2019
13:00-18:00 +0900 (JST)
04:00-09:00 (UTC/GMT)
Round 2
Sunday, July 14, 2019
19:00-24:00 +0900 (JST)
10:00-15:00 (UTC/GMT)
Round 3
Sunday, July 14, 2019
24:30-29:30 +0900 (JST)
15:30-20:30 (UTC/GMT)
(tasks for Round 1, 2, 3 are the same)


Rules that are same as IOI 2017 Rule:

Rules that are not same as IOI 2017 Rule:

Contet Site




Sample Sources

Test Data


We appreciate your feedback on our contest! Please answer the questionnaire after the contest.


joiopen at


Creative Commons License
The tasks for JOI Open Contest 2019 by JCIOI (the Japanese Committee for the IOI) is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. If you need a license other than a Creative Commons Attribution-ShareAlike 4.0 International License (CC BY-SA 4.0), please ask JCIOI.