Skip to main content

Set Matrix Zeroes

Question​

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

How can I modify a given m x n matrix so that if an element is 0, its entire row and column are set to 0 in-place?

Example 1
Input: 
[
  [1,1,1],
  [1,0,1],
  [1,1,1]
]

Output: 
[
  [1,0,1],
  [0,0,0],
  [1,0,1]
]

Solution​

all//Set Matrix Zeroes.py


class Solution:
    def setZeroes(self, matrix):
        """
        Do not return anything, modify matrix in-place instead.
        """
        rows = len(matrix)
        cols = len(matrix[0])

        row_flags = [False] * rows
        col_flags = [False] * cols

        for i in range(rows):
            for j in range(cols):
                if matrix[i][j] == 0:
                    row_flags[i] = True
                    col_flags[j] = True

        for i in range(rows):
            for j in range(cols):
                if row_flags[i] or col_flags[j]:
                    matrix[i][j] = 0