Tic-Tac-Toe Referee — Solution & Editorial
Collect the 8 lines (3 rows, 3 columns, 2 diagonals) and check each for XXX / OOO; then full-board vs ongoing.
Complexity: O(1)
Collect the 8 lines (3 rows, 3 columns, 2 diagonals) and check each for XXX / OOO; then full-board vs ongoing.
Complexity: O(1)