leetcode -- Game of Life -- 有trick，要看

class Solution(object):
def gameOfLife(self, board):
"""
:type board: List[List[int]]
:rtype: void Do not return anything, modify board in-place instead.
"""
dx = (1, 1, 1, 0, 0, -1, -1, -1)
dy = (1, 0, -1, 1, -1, 1, 0, -1)
for x in range(len(board)):
for y in range(len(board[0])):
lives = 0
for z in range(8):
nx, ny = x + dx[z], y + dy[z]
lives += self.getCellStatus(board, nx, ny)
if lives + board[x][y] == 3 or lives == 3: # cell是live只有两种情况，neibor有3个live，i.e. lives == 3.或者neibor有2个live，并且原来是live，即01,所以加起来等于3.
board[x][y] |= 2#给高位赋值1
for x in range(len(board)):
for y in range(len(board[0])):
board[x][y] >>= 1#右移到高位
def getCellStatus(self, board, x, y):
if x < 0 or y < 0 or x >= len(board) or y >= len(board[0]):
return 0
return board[x][y] & 1