289. Game of Life

289. Game of Life

题目：
https://leetcode.com/problems/game-of-life/

难度 : Medium

直接一上来就没有考虑solve it in-place,考虑的是便利，简直是born for 便利

首先我把board拓宽了，宽，高各增加了两排。

因为这样求neighbor方便，针对原来的borad，现在新的big 对于 1 -> n-1 的部分

全都有八个neighbor，用了一个2d array来记录nbrs，再根据当下的nbr来判断更新，因为不能一边在board上loop一边更新.

class Solution(object):
    def gameOfLife(self, board):
        """
        :type board: List[List[int]]
        :rtype: void Do not return anything, modify board in-place instead.
        """
        if board == [[]] : return
        row = len(board)
        col = len(board[0])
        nbrs = [[0 for j in range(col)] for i in range(row)]
        self.big = [[ 0 for j in range(col+2) ] for i in range(row+2)]
        for i in range(1,row+1):
            for j in range(1,col+1):
                self.big[i][j] = board[i-1][j-1]
            
        for i in range(1,row+1):
            for j in range(1,col+1):
                nbrs[i-1][j-1] = self.liveNeighbors(self.big,i,j)
    
        for i in range(row):
            for j in range(col):
                if board[i][j] == 1:                
                    if nbrs[i][j] < 2:
                        board[i][j] = 0
                    elif nbrs[i][j] == 2 or nbrs[i][j] == 3:
                        board[i][j] = 1
                    else:
                        board[i][j] = 0
                else:
                    if nbrs[i][j] == 3:
                        board[i][j] = 1
            
    
    def liveNeighbors(self,big,i,j):
        return self.big[i-1][j-1] + self.big[i-1][j] + self.big[i-1][j+1] + self.big[i][j-1] + self.big[i][j+1] + self.big[i+1][j-1] + self.big[i+1][j] + self.big[i+1][j+1]

谷歌了一下，大家都用到了temp 2d array嘛，哼(ˉ(∞)ˉ)唧。好吧，空间复杂度比我小。

289. Game of Life

题目：
https://leetcode.com/problems/game-of-life/

难度 : Medium

直接一上来就没有考虑solve it in-place,考虑的是便利，简直是born for 便利

首先我把board拓宽了，宽，高各增加了两排。

因为这样求neighbor方便，针对原来的borad，现在新的big 对于 1 -> n-1 的部分

全都有八个neighbor，用了一个2d array来记录nbrs，再根据当下的nbr来判断更新，因为不能一边在board上loop一边更新.

class Solution(object):
    def gameOfLife(self, board):
        """
        :type board: List[List[int]]
        :rtype: void Do not return anything, modify board in-place instead.
        """
        if board == [[]] : return
        row = len(board)
        col = len(board[0])
        nbrs = [[0 for j in range(col)] for i in range(row)]
        self.big = [[ 0 for j in range(col+2) ] for i in range(row+2)]
        for i in range(1,row+1):
            for j in range(1,col+1):
                self.big[i][j] = board[i-1][j-1]
            
        for i in range(1,row+1):
            for j in range(1,col+1):
                nbrs[i-1][j-1] = self.liveNeighbors(self.big,i,j)
    
        for i in range(row):
            for j in range(col):
                if board[i][j] == 1:                
                    if nbrs[i][j] < 2:
                        board[i][j] = 0
                    elif nbrs[i][j] == 2 or nbrs[i][j] == 3:
                        board[i][j] = 1
                    else:
                        board[i][j] = 0
                else:
                    if nbrs[i][j] == 3:
                        board[i][j] = 1
            
    
    def liveNeighbors(self,big,i,j):
        return self.big[i-1][j-1] + self.big[i-1][j] + self.big[i-1][j+1] + self.big[i][j-1] + self.big[i][j+1] + self.big[i+1][j-1] + self.big[i+1][j] + self.big[i+1][j+1]

谷歌了一下，大家都用到了temp 2d array嘛，哼(ˉ(∞)ˉ)唧。好吧，空间复杂度比我小。

原来还有高人用位运算啊，待研究。