Leetcode#73 Set Matrix Zeroes

原题地址

 

用矩形的第一行和第一列充当mask

 

代码：

 1 void setZeroes(vector<vector<int> > &matrix) {
 2         if (matrix.empty() || matrix[0].empty()) return;
 3         
 4         bool firstRow = false;
 5         bool firstCol = false;
 6         int m = matrix.size();
 7         int n = matrix[0].size();
 8         
 9         for (int i = 0; i < m; i++)
10             if (matrix[i][0] == 0) {
11                 firstCol = true;
12                 break;
13             }
14             
15         for (int j = 0; j < n; j++)
16             if (matrix[0][j] == 0) {
17                 firstRow = true;
18                 break;
19             }
20             
21         for (int i = 0; i < m; i++) {
22             for (int j = 0; j < n; j++) {
23                 if (matrix[i][j] == 0) {
24                     matrix[i][0] = 0;
25                     matrix[0][j] = 0;
26                 }
27             }
28         }
29         
30         for (int i = 1; i < m; i++)
31             if (matrix[i][0] == 0)
32                 for (int j = 1; j < n; j++)
33                     matrix[i][j] = 0;
34         
35         for (int j = 1; j < n; j++)
36             if (matrix[0][j] == 0)
37                 for (int i = 1; i < m; i++)
38                     matrix[i][j] = 0;
39         
40         if (firstCol)
41             for (int i = 0; i < m; i++)
42                 matrix[i][0] = 0;
43         if (firstRow)
44             for (int j = 0; j < n; j++)
45                 matrix[0][j] = 0;
46 }

 

posted @ 2015-01-28 14:54  李舜阳  阅读(128)  评论(0)  编辑  收藏  举报