class Solution:
    def setZeroes(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        if not len(matrix) or not len(matrix[0]): return 
        n, m = len(matrix), len(matrix[0])
        r0, c0 = 1, 1
        #遍历第一列是否有0
        for i in range(n): 
            if not matrix[i][0]: c0 = 0
        #遍历第一行是否有0
        for i in range(m): 
            if not matrix[0][i]: r0 = 0
        #检查每一列是否有0用第一列记录
        for j in range(1,m):
            for i in range(n):
                if not matrix[i][j]: matrix[0][j] = 0
        #检查每一行是否有0用第一行记录
        for i in range(1,n):
            for j in range(m):
                if not matrix[i][j]: matrix[i][0] = 0
        #如果第j列有0，那么这一列所有数=0
        for j in range(1, m):
            if not matrix[0][j]:
                for i in range(n):
                    matrix[i][j] = 0
        #如果第i行有0，那么这一行所有数=0
        for i in range(1,n):
            if not matrix[i][0]:
                for j in range(m):
                    matrix[i][j] = 0
        #如果r0是0，那么第一行所有数=0
        if not r0: 
            for j in range(m): matrix[0][j] = 0
        #如果c0是0，那么第一列所有数 = 0
        if not c0: 
            for i in range(n): matrix[i][0] = 0