Hi all,

The first stage of the IOI 2026 China Team Selection has just concluded. The top 50 48 participants from the 2025 National Olympiad in Informatics (NOI) will compete for a spot on the Chinese national team for IOI 2026.

The rule of selecting CHN team this year:

• Homework (10%): also known as mutual tests, where the students were asked to prepare a task, and solve 120 problems on the QOJ training tasks list
• First stage (CTT; 54%; Dec 2, 2025 — Dec 4, 2025): three contests in classic olympiad format, where each contest worthes 18% of the score. Top 30 participants will advance to the final stage.
• Final stage (CTS; 36%; Feb 6, 2026 — Feb 13, 2026): two contests in classic olympiad format, where each contest worthes 18% of the score.

The detailed selection rule is available here (in Chinese). After all the selections, top 6 students will be qualified to the interview & thesis defense stage, and four of them will be selected to represent China in IOI 2026.

The current scoreboard can be found here. Thanks to Crysfly for compiling this document.

Past problems of the China IOI Team Selections can be found here (first stage and final stage), and this year's task is available here. You are welcomed to try these tasks or pratice them, but we will not hold an open mirror for these contests.

CTS 2026 Prediction Game

As our usual fun tradition, we will host The CTS 2026 Prediction Game at our Voting Game Site.

You need to predict the 1st to 6th place winners. Each contestant can only be nominated once.

1. For each contestant you nominate who finishes in the top 4, let $R$ be the actual rank of the contestant and $r$ be the rank you predicted ($1 \le r \le 4$):
   • You receive $10$ points $1 \le R \le 4$, and a bonus $3$ points if $R = r$
   • You receive $5$ points $5 \le R \le 6$
   • You receive $2$ points $7 \le R \le 10$
2. For each contestant you nominate who finishes in ranked 5 or 6, let $R$ be the actual rank of the contestant and $r$ be the rank you predicted ($5 \le r \le 6$):
   • You receive $4$ points $1 \le R \le 4$
   • You receive $8$ points $5 \le R \le 6$, and a bonus $3$ points if $R = r$
   • You receive $3$ points $7 \le R \le 10$
3. If you leave a rank blank (i.e., choose not to make a prediction for that rank), you receive 1 point for that empty slot.
4. There is a bonus question asking if anyone ranked 5 or 6 will enter the national team.