73.py

class Solution(object):
    def setZeroes(self, matrix):
        """
        :type matrix: List[List[int]]
        :rtype: void Do not return anything, modify matrix in-place instead.
        """
        col0 = 1
        for row in range(len(matrix)):
        	if matrix[row][0] == 0:
        		col0 = 0
        	for col in range(1, len(matrix[0])):
        		if matrix[row][col] == 0:
        			matrix[row][0] = 0
        			matrix[0][col] = 0
        for row in range(len(matrix)-1, -1, -1):
        	for col in range(len(matrix[0])-1, 0, -1):
        		if matrix[row][0] == 0 or matrix[0][col] == 0:
        			matrix[row][col] = 0
        	if col0 == 0:
        		matrix[row][0] = 0