https://leetcode-cn.com/problems/set-matrix-zeroes
Given an m x n integer matrix matrix, if an element is 0, set its entire row and column to 0's.
You must do it in place.
Example 1:
Input: matrix = [[1,1,1],[1,0,1],[1,1,1]]
Output: [[1,0,1],[0,0,0],[1,0,1]]
Example 2:
Input: matrix = [[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]]
Constraints:
m == matrix.length
n == matrix[0].length
1 <= m, n <= 200
-2^31 <= matrix[i][j] <= 2^31 - 1
Follow up:
A straightforward 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.
"""
flag_col0,flag_row0=False,False
m,n=len(matrix),len(matrix[0])
for i in range(m):
if matrix[i][0]==0:
flag_col0=True
break
for j in range(n):
if matrix[0][j]==0:
flag_row0=True
break
for i in range(1,m):
for j in range(1,n):
if matrix[i][j]==0:
matrix[i][0],matrix[0][j]=0,0
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 flag_col0:
for i in range(m):
matrix[i][0]=0
if flag_row0:
for j in range(n):
matrix[0][j]=0