# 73 Set Matrix Zeroes

Given amxnmatrix, if an element is 0, set its entire row and column to 0. Do it in place.
Complexity: O(n) time and space
The Idea: Not O(1) space, but other wise minimally efficient. We store the rows and cols of the located zeros into sets, as to avoid iterating through rows and columns that are going to be zeroed out anyway.
class Solution:
def setZeroes(self, matrix):
"""
:type matrix: List[List[int]]
:rtype: void Do not return anything, modify matrix in-place instead.
"""
row_s = len(matrix)
col_s = len(matrix)
set_r = set()
set_c = set()
for i in range(row_s):
for j in range(col_s):
if (matrix[i][j] == 0):
j = 0
# zero out the rows
for r in set_r:
matrix[r] =  * col_s
# zero out the cols
for c in set_c:
for iter in range(0, row_s):
matrix[iter][c] = 0
Testing
obj = Solution()
matrix = [[1,2,3],
[4,5,0],
[8,9,10]]
obj.setZeroes(matrix)
print(matrix)
matrix2 = [[0,2,3],
[4,5,6],
[8,9,0]]
obj.setZeroes(matrix2)
print(matrix2)
matrix3 = [[0,1]]
obj.setZeroes(matrix3)
print(matrix3)
matrix4 = [,
]
obj.setZeroes(matrix4)
print(matrix4)