game-of-life.py

class Solution(object):
    def gameOfLife(self, board):
        """
        :type board: List[List[int]]
        :rtype: void Do not return anything, modify board in-place instead.
        """
        def helper(board, p, q):
            cnt = 0
            for i in xrange(p - 1, p + 2):
                for j in xrange(q - 1, q + 2):
                    if i == p and j == q:
                        continue
                    if 0 <= i < len(board) and 0 <= j < len(board[0]) and board[i][j] & 1:
                        cnt += 1
            if cnt == 3 or (board[p][q] == 1 and cnt == 2):
                board[p][q] |= 2
        
        for i in xrange(0, len(board)):
            for j in xrange(0, len(board[0])):
                helper(board, i, j)

        for i in xrange(0, len(board)):
            for j in xrange(0, len(board[0])):
                board[i][j] >>= 1