Set Matrix Zeroes

Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.

click to show follow up.
Follow up:
Did you use extra space?

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?

Solution:

class Solution {
public:
void setZeroes(vector<vector<int>>& matrix) {
int m = matrix.size();
if(!m) return ;
int n = matrix[0].size();
if(!n) return ;
int x = -1, y = -1;
for(int i = 0; i < m; ++i)
for(int j = 0; j < n; ++j)
{
if(!matrix[i][j])
{
if(x == -1 && y == -1)
{
x = i;
y = j;
}
else
{
matrix[i][y] = 0;
matrix[x][j] = 0;
}
}
}
if(x != -1 && y != -1)
{
for(int i = 0; i < n; ++i)
{
if(!matrix[x][i] && i != y)
{
for(int j = 0; j < m; ++j) matrix[j][i] = 0;
}
}
for(int i = 0; i < m; ++i)
{
if(!matrix[i][y])
{
for(int j = 0; j < n; ++j) matrix[i][j] = 0;
}
}
for(int i = 0; i < m; ++i) matrix[i][y] = 0;
}
}
};