73. Set Matrix Zeroes

Medium

Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in-place.

😇 Solution

O(nm)

class Solution:
    def setZeroes(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        n = len(matrix)
        m = len(matrix[0])
        
        zero_i = set()
        zero_j = set()
        for i in range(n):
            for j in range(m):
                if matrix[i][j] == 0:
                    zero_i.add(i)
                    zero_j.add(j)
     
        for i in range(n):
            for j in range(m):
                if (i in zero_i) or (j in zero_j):
                    matrix[i][j] = 0