leetcode

Game of Life

Game of Life

another solution - 36ms

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class Solution:
    def gameOfLife(self, board):
        """
        :type board: List[List[int]]
        :rtype: void Do not return anything, modify board in-place instead.
        """
        if not board or not board[0]: return
        m, n = len(board), len(board[0])
        for i, row in enumerate(board):
            for j, ele in enumerate(row):
                count = 0
                for a in range(max(0, i - 1), min(i + 2, m)):
                    for b in range(max(0, j - 1), min(j + 2, n)):
                        # skip i, j itself, (a, b) is (i, j)'s eight neighbors
                        # should count current_alive(1) and formerly_alive(2)
                        if (a, b) != (i, j) and 1 <= board[a][b] <= 2:
                            count += 1
                if board[i][j] == 0:
                    if count == 3:
                        board[i][j] = 3
                else:
                    if count < 2 or count > 3:
                        board[i][j] = 2
        for i in range(m):
            for j in range(n):
                if board[i][j] == 2:
                    board[i][j] = 0
                elif board[i][j] == 3:
                    board[i][j] = 1

test code

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In [16]: in_arr = [[0,1,0],[0,0,1],[1,1,1],[0,0,0]]
In [17]: s = Solution(); s.gameOfLife(in_arr)
In [18]: in_arr
Out[18]: [[0, 0, 0], [1, 0, 1], [0, 1, 1], [0, 1, 0]]

leet code

康威生命游戏