hdu 1072 bfs

 1 #include <iostream>
 2 #include <cstring>
 3 #include <cstdio>
 4 #include <queue>
 5 using namespace std;
 6 
 7 const int N = 8;
 8 int maze[N][N];
 9 int visit[N][N];
10 int dx[] = { 0, 0, 1, -1 };
11 int dy[] = { 1, -1, 0, 0 };
12 int sx, sy, ex, ey;
13 int n, m;
14 
15 bool ok( int x, int y )
16 {
17     return x >= 0 && x < n && y >= 0 && y < m && maze[x][y] != 0;
18 }
19 
20 struct Node 
21 {
22     int x, y, step;
23     Node(){}
24     Node( int _x, int _y, int _step )
25     {
26         x = _x, y = _y, step = _step;
27     }
28 };
29 
30 queue<Node> q;
31 
32 int bfs()
33 {
34     while ( !q.empty() ) q.pop();
35     memset( visit, 0, sizeof(visit) );
36     visit[sx][sy] = 6;
37     q.push( Node( sx, sy, 0 ) );
38     while ( !q.empty() )
39     {
40         Node cur = q.front();
41         q.pop();
42         if ( cur.x == ex && cur.y == ey ) return cur.step;
43         if ( visit[cur.x][cur.y] == 1 ) continue;
44         for ( int i = 0; i < 4; i++ )
45         {
46             int xx = cur.x + dx[i];
47             int yy = cur.y + dy[i];
48             if ( ok( xx, yy ) )
49             {
50                 int r = visit[cur.x][cur.y] - 1;
51                 if ( maze[xx][yy] == 4 ) r = 6;
52                 if ( r > visit[xx][yy] )
53                 {
54                     q.push( Node( xx, yy, cur.step + 1 ) );
55                     visit[xx][yy] = r;
56                 }
57             }
58         }
59     }
60     return -1;
61 }
62 
63 int main ()
64 {
65     int t;
66     scanf("%d", &t);
67     while ( t-- )
68     {
69         scanf("%d%d", &n, &m);
70         for ( int i = 0; i < n; i++ )
71         {
72             for ( int j = 0; j < m; j++ )
73             {
74                 scanf("%d", &maze[i][j]);
75                 if ( maze[i][j] == 2 )
76                 {
77                     sx = i;
78                     sy = j;
79                     maze[i][j] = 1;
80                 }
81                 else if ( maze[i][j] == 3 )
82                 {
83                     ex = i;
84                     ey = j;
85                     maze[i][j] = 1;
86                 }
87             }
88         }
89         int ans = bfs();
90         printf("%d\n", ans);
91     }
92     return 0;    
93 }