leetcode[73]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.
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.empty())return; int row=matrix.size(); if(matrix[0].empty())return; int col=matrix[0].size(); int flagRow0=0,flagCol0=0; for(int j=0;j<col;j++) { if(matrix[0][j]==0)flagRow0=1; } for(int i=0;i<row;i++) { if(matrix[i][0]==0)flagCol0=1; } for (int i=1;i<row;i++) { for (int j=1;j<col;j++) { if (matrix[i][j]==0) { matrix[0][j]=0; matrix[i][0]=0; } } } for (int i=1;i<row;i++) { if(matrix[i][0]==0) { for (int j=1;j<col;j++) { matrix[i][j]=0; } } } for (int j=1;j<col;j++) { if(matrix[0][j]==0) { for (int i=1;i<row;i++) { matrix[i][j]=0; } } } if(flagRow0==1) { for(int j=0;j<col;j++)matrix[0][j]=0; } if(flagCol0==1) { for(int i=0;i<row;i++)matrix[i][0]=0; } return; } };