Technical Screen

A Tic-Tac-Toe Sequence-Counting Problem in the Coding Round

DecagonAI Engineer · Technical Screen · Jul 2026

I recently interviewed for Decagon's AI Engineer role, first round (the coding round), and got a question that doesn't have an exact match on LeetCode, so I wanted to share it. Problem Two players take turns placing marks on a 3x3 board, X goes first, then O, alternating. A game is the entire sequence of moves from an empty board to the end of the game. The game ends immediately as soon as one si…

Shared by a candidate · reported Jul 2026. Interview formats change; use it as a guide, not a script.