Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in-place.
Example 1:
Input:
[
[1,1,1],
[1,0,1],
[1,1,1]
]
Output:
[
[1,0,1],
[0,0,0],
[1,0,1]
]
Example 2:
Input:
[
[0,1,2,0],
[3,4,5,2],
[1,3,1,5]
]
Output:
[
[0,0,0,0],
[0,4,5,0],
[0,3,1,0]
]
Follow up:
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:
def setZeroes(self, matrix: List[List[int]]) -> None:
"""
Do not return anything, modify matrix in-place instead.
"""
col_zero = False
for i in range(len(matrix)):
if matrix[i][0] == 0:
col_zero = True
for j in range(1, len(matrix[0])):
if matrix[i][j] == 0:
matrix[0][j] = matrix[i][0] = 0
for i in range(1, len(matrix)):
for j in range(1, len(matrix[0])):
if not matrix[0][j] or not matrix[i][0]:
matrix[i][j] = 0
if matrix[0][0] == 0:
for j in range(len(matrix[0])):
matrix[0][j] = 0
if col_zero:
for i in range(len(matrix)):
matrix[i][0] = 0