Set Matrix Zeroes

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

click to show follow up.

Follow up: Did you use extra space? A straight forward solution using O(mn) space is probably a bad idea. A simple improvement uses O(m + n) space, but still not the best solution. Could you devise a constant space solution?

URL: https://leetcode.com/problems/set-matrix-zeroes/

class Solution(object):
    def setZeroes(self, matrix):
        """
        :type matrix: List[List[int]]
        :rtype: void Do not return anything, modify matrix in-place instead.
        """
        if matrix == None or len(matrix) == 0:
            pass
        elif len(matrix) == 1 and len(matrix[0]) == 1:
            pass
        else:
            rows_with_0 = [False]*len(matrix)
            cols_with_0 = [False]*len(matrix[0])
            for i in range(len(matrix)):
                for j in range(len(matrix[0])):
                    if matrix[i][j] == 0:
                        rows_with_0[i] = True
                        cols_with_0[j] = True

            for i in range(len(matrix)):
                for j in range(len(matrix[0])):
                    if rows_with_0[i] or cols_with_0[j]:
                        matrix[i][j] = 0

Constant Space Solution:

class Solution(object):
    def setZeroes(self, matrix):
        """
        :type matrix: List[List[int]]
        :rtype: void Do not return anything, modify matrix in-place instead.
        """
        first_row = False
        first_col = False

        for j in range(len(matrix[0])):
            if matrix[0][j] == 0:
                first_row = True

        for i in range(len(matrix)):
            if matrix[i][0] == 0:
                first_col = True


        for i in range(1, len(matrix)):
            for j in range(1, len(matrix[0])):
                if matrix[i][j] == 0:
                    matrix[i][0] = 0
                    matrix[0][j] = 0

        for i in range(1, len(matrix)):
            for j in range(1, len(matrix[0])):
                if matrix[i][0] == 0 or matrix[0][j] == 0:
                    matrix[i][j] = 0

        if first_col:
            for i in range(len(matrix)):
                matrix[i][0] = 0

        if first_row:
            for i in range(len(matrix[0])):
                matrix[0][i] = 0