Set_Matrix_Zeroes.py

"""
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?
"""

class Solution:
    # @param matrix, a list of lists of integers
    # RETURN NOTHING, MODIFY matrix IN PLACE.
    def setZeroes(self, matrix):
        n = len(matrix[0])
        m = len(matrix)
        zero_row = False
        zero_col = False

        for i in range(m):
            for j in range(n):
                if matrix[i][j] == 0:
                    if i == 0:
                        zero_row = True
                    if j == 0:
                        zero_col = True
                    matrix[i][0] = matrix[0][j] = 0

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

        if zero_row:
            for j in range(n):
                matrix[0][j] = 0

        return matrix