Introduction

This last weekend, I took part in SEATST (Southeast Asia Team Selection Test) 2026. A few people (YSH2020 and Tyx2019) have posted blogs on the contest.

SEATST is a IOI format (2 days, 3 problems in 5 hours on each day) contest made in 2025 that "replaced APIO as a crucial component of IOI selection in Singapore." (this statement is directly quoted from the SEATST website found here).

Looking at my APIO scores for these 2 years and my SEATST scores, I believe I am one of the largest beneficiaries for the shift away from APIO towards SEATST. Here are my scores:

APIO 2025: 87/300, 10th in SG SEATST 2025: 380/600, 3rd in SG APIO 2026: 13.5/300, 21st in SG (I know my strategy was kinda screwed but whatever) SEATST 2026: 419/600, 4th in SG

I had quite an interesting experience in this year's SEATST, best summed up by my score distribution:

(300 on day 1, 119 on day 2)

This is also why I'm only doing editorial for day 1.

The contest quality was actually pretty good.