hdu--1010--dfs

 1 #include <iostream>
 2 #include <cstring>
 3 using namespace std;
 4 
 5 int n , m , t;
 6 int endx , endy;
 7 bool flag;
 8 char maze[10][10];
 9 bool vis[10][10];
10 int dir[4][2]={1,0,-1,0,0,1,0,-1};
11 int abs( int x )
12 {
13     return x>0?x:-x;
14 }
15 
16 void dfs( int x , int y , int cnt )
17 {
18     if( cnt>t || x<0 || x>=n || y<0 || y>=m || flag )
19         return;
20      int temp = t - cnt - abs(x - endx) - abs(y - endy);
21     if( temp < 0 || temp & 1)
22         return;
23     if( maze[x][y] == ‘D‘ && t == cnt )
24     {
25         flag = true;
26         return;
27     }
28     for( int i = 0 ; i<4 ; i++ )
29     {
30         int xx = x + dir[i][0];
31         int yy = y + dir[i][1];
32         if( maze[xx][yy]!=‘X‘ && !vis[xx][yy] )
33         {
34             vis[xx][yy] = true;
35             dfs( xx , yy , cnt+1 );
36             if( flag )
37                 return;
38             vis[xx][yy] = false;
39         }
40     }
41     return;
42 }
43 
44 int main()
45 {
46     int block , stx , sty;
47     while( cin >> n >> m >> t )
48     {
49         flag = false;
50         block = 0;
51         if( !n && !m && !t )
52             break;
53         memset( vis , false , sizeof(vis) );
54         for( int i = 0 ; i<n ; i++ )
55         {
56             for( int j = 0 ; j<m ; j++ )
57             {
58                 cin >> maze[i][j];
59                 if( maze[i][j] == ‘S‘ )
60                 {
61                     stx = i;
62                     sty = j;
63                     vis[stx][sty] = true;
64                 }
65                 else if( maze[i][j] == ‘D‘ )
66                 {
67                     endx = i;
68                     endy = j;
69                 }
70                 else if( maze[i][j] == ‘.‘ )
71                 {
72                     block++;
73                 }
74             }
75         }
76         if( block+1<t )
77         {
78             cout << "NO" << endl;
79             continue;
80         }
81         dfs( stx , sty , 0 );
82         if( flag )
83             cout << "YES" << endl;
84         else
85             cout << "NO" << endl;
86     }
87     return 0;
88 }