MathDB
Grid game

Source: Czech-Polish-Slovak Match 2022 P1

September 3, 2022
combinatorics

Problem Statement

Let k2022k \leq 2022 be a positive integer. Alice and Bob play a game on a 2022×20222022 \times 2022 board. Initially, all cells are white. Alice starts and the players alternate. In her turn, Alice can either color one white cell in red or pass her turn. In his turn, Bob can either color a k×kk \times k square of white cells in blue or pass his turn. Once both players pass, the game ends and the person who colored more cells wins (a draw can occur). For each 1k20221 \leq k \leq 2022, determine which player (if any) has a winning strategy.