Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.
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?
class Solution {
public:
void setZeroes(vector<vector<int> > &matrix)
{
if(matrix.size()==0 || matrix[0].size()==0) return;
vector<int> zerox;
vector<int> zeroy;
for(int i=0;i<matrix.size();i++)
for(int j=0;j<matrix[0].size();j++)
if(matrix[i][j]==0)
{
zerox.push_back(i);
zeroy.push_back(j);
}
for(int i=0;i<zerox.size();i++)
{
for(int k=0;k<matrix.size();k++)
matrix[k][zeroy[i]]=0;
for(int k=0;k<matrix[0].size();k++)
matrix[zerox[i]][k]=0;
}
}
};
public:
void setZeroes(vector<vector<int> > &matrix)
{
if(matrix.size()==0 || matrix[0].size()==0) return;
vector<int> zerox;
vector<int> zeroy;
for(int i=0;i<matrix.size();i++)
for(int j=0;j<matrix[0].size();j++)
if(matrix[i][j]==0)
{
zerox.push_back(i);
zeroy.push_back(j);
}
for(int i=0;i<zerox.size();i++)
{
for(int k=0;k<matrix.size();k++)
matrix[k][zeroy[i]]=0;
for(int k=0;k<matrix[0].size();k++)
matrix[zerox[i]][k]=0;
}
}
};