hdu 1885 bfs+状压

和上一个题基本一样。

  1 #include <iostream>
  2 #include <cstring>
  3 #include <cstdio>
  4 #include <cctype>
  5 #include <queue>
  6 #include <map>
  7 using namespace std;
  8 
  9 const int N = 101;
 10 char maze[N][N];
 11 bool visit[N][N][1 << 4];
 12 int dx[] = { 0, 0, 1, -1 };
 13 int dy[] = { 1, -1, 0, 0 };
 14 int n, m, sx, sy;
 15 map<char, int> mp;
 16 
 17 void init()
 18 {
 19     mp['B'] = 0;    mp['b'] = 0;
 20     mp['Y'] = 1;    mp['y'] = 1;
 21     mp['R'] = 2;    mp['r'] = 2;
 22     mp['G'] = 3;    mp['g'] = 3;
 23 }
 24 
 25 bool ok( int x, int y )
 26 {
 27     return x >= 0 && x < n && y >= 0 && y < m;
 28 }
 29 
 30 struct Node 
 31 {
 32     int x, y, step, state;
 33     Node(){}
 34     Node( int _x, int _y, int _step, int _state )
 35     {
 36         x = _x, y = _y, step = _step, state = _state;
 37     }
 38 };
 39 
 40 bool uc( char ch )
 41 {
 42     return ch == 'B' || ch == 'Y' || ch == 'R' || ch == 'G';
 43 }
 44 
 45 bool lc( char ch )
 46 {
 47     return ch == 'b' || ch == 'y' || ch == 'r' || ch == 'g';
 48 }
 49 
 50 queue<Node> q;
 51 
 52 int bfs()
 53 {
 54     while ( !q.empty() ) q.pop();
 55     memset( visit, false, sizeof(visit) );
 56     q.push( Node( sx, sy, 0, 0 ) );
 57     visit[sx][sy][0] = true;
 58     while ( !q.empty() )
 59     {
 60         Node cur = q.front();
 61         q.pop();
 62         if ( maze[cur.x][cur.y] == 'X' ) return cur.step;
 63         for ( int i = 0; i < 4; i++ )
 64         {
 65             int xx = cur.x + dx[i];
 66             int yy = cur.y + dy[i];
 67             if ( ok( xx, yy ) )
 68             {
 69                 if ( maze[xx][yy] == '#' ) continue;
 70                 if ( uc( maze[xx][yy] ) )
 71                 {
 72                     int tmp = ( 1 << mp[maze[xx][yy]] );
 73                     if ( ( cur.state & tmp ) && !visit[xx][yy][cur.state] )
 74                     {
 75                         q.push( Node( xx, yy, cur.step + 1, cur.state) );
 76                         visit[xx][yy][cur.state] = true;
 77                     }
 78                 }
 79                 else if ( lc( maze[xx][yy] ) )
 80                 {
 81                     int tmp = ( 1 << mp[maze[xx][yy]] );
 82                     if ( !visit[xx][yy][cur.state | tmp] )
 83                     {
 84                         q.push( Node( xx, yy, cur.step + 1, cur.state | tmp ) );
 85                         visit[xx][yy][cur.state | tmp] = true;
 86                     }
 87                 }
 88                 else
 89                 {
 90                     if ( !visit[xx][yy][cur.state] )
 91                     {
 92                         q.push( Node( xx, yy, cur.step + 1, cur.state ) );
 93                         visit[xx][yy][cur.state] = true;
 94                     }
 95                 }
 96             }
 97         }
 98     }
 99     return -1;
100 }
101 
102 int main ()
103 {
104     init();
105     while ( scanf("%d%d", &n, &m) != EOF )
106     {
107         if ( !n && !m ) break;
108         int x = 0;
109         for ( int i = 0; i < n; i++ )
110         {
111             scanf("%s", maze[i]);
112             for ( int j = 0; j < m; j++ )
113             {
114                 if ( maze[i][j] == '*' )
115                 {
116                     sx = i;
117                     sy = j;
118                     maze[i][j] = '.';
119                 }
120                 else if ( maze[i][j] == 'X' )
121                 {
122                     x++;
123                 }
124             }
125         }
126         if ( x == 0 || ( x = bfs() ) == -1 )
127         {
128             printf("The poor student is trapped!\n");
129         }
130         else
131         {
132             printf("Escape possible in %d steps.\n", x);
133         }
134     }
135     return 0;    
136 }

 

posted @ 2015-08-14 15:22  hxy_has_been_used  阅读(146)  评论(0)  编辑  收藏  举报