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## Problem

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]
]


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?

## Code

class Solution {
public void setZeroes(int[][] matrix) {
boolean rowZero = false;
boolean colZero = false;

int m = matrix.length;
int n = matrix[0].length;

for(int i = 0; i < m; i++){
for(int j = 0; j < n; j++){
if(matrix[i][j] == 0){
if(i == 0) rowZero = true;
if(j == 0) colZero = true;

matrix[i][0] = 0;
matrix[0][j] = 0;
}
}
}

for(int j = 1; j < n; j++){
if(matrix[0][j] == 0){
for(int i = 1; i < m; i++){
matrix[i][j] = 0;
}
}
}

for(int i = 1; i < m; i++){
if(matrix[i][0] == 0){
for(int j = 0; j < n; j++){
matrix[i][j] = 0;
}
}
}

if(rowZero){
for(int j = 0; j < n; j++){
matrix[0][j] = 0;
}
}

if(colZero){
for(int i = 0; i < m; i++){
matrix[i][0] = 0;
}
}
}
}