Problem

Source: JBMO Shortlist 2021

Tags: Junior, Balkan, shortlist, 2021, combinatorics, game, board coloring



Given an $m \times n$ table consisting of $mn$ unit cells. Alice and Bob play the following game: Alice goes first and the one who moves colors one of the empty cells with one of the given three colors. Alice wins if there is a figure, such as the ones below, having three different colors. Otherwise Bob is the winner. Determine the winner for all cases of $m$ and $n$ where $m, n \ge 3$. Proposed by Toghrul Abbasov, Azerbaijan


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