= Tic-tac-toe
{wiki}
= Noughts and crosses
{synonym}
A two-player <game> on nine positions arranged in a three-by-three grid. Players alternate marking empty positions and stop when one has a full row, column or diagonal, or when the board is full. A game search must stop at the first win. Distinct move histories can reach the same position; canonical occupancy <sets> or <bitboards> make that equality available to <memoization>. Quotienting by board symmetry changes the requested output unless distinct oriented positions are subsequently restored.
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