find-winner-on-a-tic-tac-toe-game.py

# Time:  O(1)
# Space: O(1)

class Solution(object):
    def tictactoe(self, moves):
        """
        :type moves: List[List[int]]
        :rtype: str
        """
        row, col = [[0]*3 for _ in xrange(2)], [[0]*3 for _ in xrange(2)]
        diag, anti_diag = [0]*2, [0]*2
        p = 0
        for r, c in moves:
            row[p][r] += 1
            col[p][c] += 1
            diag[p] += r == c
            anti_diag[p] += r+c == 2
            if 3 in (row[p][r], col[p][c], diag[p], anti_diag[p]):
                return "AB"[p]
            p ^= 1
        return "Draw" if len(moves) == 9 else "Pending"