矩阵中的路径

 1 public class Solution {
 2     public boolean dfs(int x, int y, char[] matrix, int rows, int cols, char[] str, int pos, boolean[][]vis) {
 3         int [][]shift = new int[][]{{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
 4         boolean flag = false;
 5         if (pos == str.length) return true;
 6         for (int i = 0; i < 4; ++i) {
 7             int posx = x + shift[i][0];
 8             int posy = y + shift[i][1];
 9             if (flag) return true;
10             if (posx < rows && posy < cols && posx >= 0 && posy >= 0 && !vis[posx][posy]) {
11                 char c = matrix[posx * cols + posy];
12                 if (c == str[pos]) {
13                     vis[posx][posy] = true;
14                     flag = flag || dfs(posx, posy, matrix, rows, cols, str, pos + 1, vis);
15                     vis[posx][posy] = false;
16                 }
17             }
18         }
19         return flag;
20         
21     }
22     public boolean hasPath(char[] matrix, int rows, int cols, char[] str)
23     {
24         
25         boolean [][]vis = new boolean [rows + 1][cols + 1];
26         boolean flag = false;
27         
28         for (int i = 0; i < rows; ++i) {
29             for (int j = 0; j < cols; ++j) {
30                 char c = matrix[i * cols + j];
31                 if(flag) return true;
32                 if (c == str[0]) {
33                     vis[i][j] = true;
34                     flag = flag || dfs(i, j, matrix, rows, cols, str, 1, vis);
35                     vis[i][j] = false;
36                 }
37             }
38         }
39         return flag;
40     }
41 
42 
43 }