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?
Code:
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class
Solution {
public:
void
setZeroes(vector<vector<int> > &matrix) {
int
m=matrix.size();
int
n=matrix[0].size();
int
firstrow=0;
int
firstcol=0;
for(int
i=0;i<n;i++)
if(matrix[0][i]==0){
firstrow=1;
break;
}
for(int
j=0;j<m;j++)
if(matrix[j][0]==0){
firstcol=1;
break;
}
for(int
j=0;j<m;j++)
for(int
i=0;i<n;i++){
if(matrix[j][i]==0){
matrix[j][0]=0;
matrix[0][i]=0;
}
}
for(int
i=1;i<n;i++)
if(matrix[0][i]==0)
for(int
j=1;j<m;j++)
matrix[j][i]=0;
for(int
j=1;j<m;j++)
if(matrix[j][0]==0)
for(int
i=1;i<n;i++)
matrix[j][i]=0;
if(firstrow==1)
for(int
i=0;i<n;i++)
matrix[0][i]=0;
if(firstcol==1)
for(int
j=1;j<m;j++)
matrix[j][0]=0;
}
}; |