leetcode

Set Matrix Zeroes

Set Matrix Zeroes

O(1) Space Version - 92ms

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class Solution:
    def setZeroes(self, matrix):
        """
        :type matrix: List[List[int]]
        :rtype: void Do not return anything, modify matrix in-place instead.
        """
        m = len(matrix)
        if m == 0:
            return
        n = len(matrix[0])
        row_zero = False
        for i in range(m):
            if matrix[i][0] == 0:
                row_zero = True
        col_zero = False
        for j in range(n):
            if matrix[0][j] == 0:
                col_zero = True
        for i in range(1, m):
            for j in range(1, n):
                if matrix[i][j] == 0:
                    matrix[i][0] = 0
                    matrix[0][j] = 0
        for i in range(1, m):
            if matrix[i][0] == 0:
                for j in range(1, n):
                    matrix[i][j] = 0
        for j in range(1, n):
            if matrix[0][j] == 0:
                for i in range(1, m):
                    matrix[i][j] = 0
        if col_zero:
            for j in range(n):
                matrix[0][j] = 0
        if row_zero:
            for i in range(m):
                matrix[i][0] = 0

test code

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In [23]: m = [[1,1,1],[1,0,1],[1,1,1]]
In [24]: s = Solution(); s.setZeroes(m)
In [25]: m
Out[25]: [[1, 0, 1], [0, 0, 0], [1, 0, 1]]

leet code