[BFS][NOI题库][poj2157]Maze

  1 #include <stdio.h>
  2 #include <string.h>
  3 #include <algorithm>
  4 #define MAX 25
  5 using namespace std;
  6 
  7 struct dui{
  8     int r, c; // hang lie
  9 }queue[ MAX * MAX ];
 10 
 11 struct men{
 12     int key_sum, key_num;
 13 }door[ 6 ];
 14 
 15 int m, n;
 16 char map[ MAX ][ MAX ];
 17 bool vis[ MAX ][ MAX ];
 18 bool vis_door[ MAX ][ MAX ];
 19 
 20 int wx[ 5 ] = { 0, -1, 0, 1, 0};
 21 int wy[ 5 ] = { 0 ,0, 1, 0, -1};
 22 
 23 bool able( int x, int y )
 24 {
 25     if( x > 0 && x <= m && y > 0 && y <= n)
 26         return true;
 27     else return false;
 28 }
 29 
 30 int main()
 31 {
 32     int i, j;
 33     int r, c;
 34     char tmp, tt;
 35     while( true ){
 36         scanf("%d%d", &m ,&n);
 37         if( m == 0 && n == 0 ) break;
 38         memset( vis, 0, sizeof( vis ));
 39         memset( door, 0, sizeof( door ));
 40         memset( vis_door, 0, sizeof( vis_door ));
 41         for( i = 1; i <= m; i++ ){
 42             scanf("%s", map[ i ] + 1);
 43             for( j = 1; j <= n; j++ ){
 44                 if( map[ i ][ j ] >= ‘a‘ && map[ i ][ j ] <= ‘e‘){
 45                     door[ map[ i ][ j ] - ‘a‘ + 1 ].key_sum ++;
 46                 }
 47                 if( map[ i ][ j ] == ‘S‘ ){
 48                     queue[ 0 ].r = i;
 49                     queue[ 0 ].c = j;
 50                     vis[ i ][ j ] = 1;
 51                 }
 52             }
 53         }
 54         
 55         int head = 0, tail = 1;
 56         bool finded = false;
 57         bool newdoor = true;
 58         
 59         while( newdoor ){
 60             while( !finded && head < tail){
 61                 for( i = 1; i <= 4; i++ ){
 62                     r = queue[ head ].r + wx[ i ];
 63                     c = queue[ head ].c + wy[ i ];
 64                     
 65                     if( map[ r ][ c ] == ‘G‘ ){
 66                         finded = true;
 67                         break;
 68                     }
 69 
 70                     if( !vis[ r ][ c ] && able( r, c ) && map[ r ][ c ] != ‘X‘){
 71                         tmp = map[ r ][ c ];
 72                         
 73                         if( tmp >= ‘A‘ && tmp <= ‘E‘){
 74                             vis_door[ r ][ c ] = true;
 75                             continue;
 76                         }
 77                         
 78                         if( tmp >= ‘a‘ && tmp <= ‘e‘ ){
 79                             door[ tmp - ‘a‘ + 1 ].key_num++;
 80                         }
 81                         vis[ r ][ c ] = true;
 82                         queue[ tail ].r = r;
 83                         queue[ tail ].c = c;
 84                         tail++;
 85                     }
 86                 }
 87                 head++;
 88             }
 89             if( finded ) break;
 90             
 91             newdoor = false;
 92             
 93             for( r = 1; r <= m; r++ ){
 94                 for( c = 1; c <= n; c++ ){
 95                     tmp = map[ r ][ c ];
 96                     if( tmp >= ‘A‘ && tmp <= ‘E‘ && vis_door[ r ][ c ] && !vis[ r ][ c ]){
 97                         tt = tmp - ‘A‘ + 1;
 98                         if( door[ tt ].key_sum > 0 && door[ tt ].key_sum == door[ tt ].key_num ){
 99                             vis[ r ][ c ] = true;
100                             queue[ tail ].r = r;
101                             queue[ tail ].c = c;
102                             tail++;
103                             newdoor = true;
104                         }
105                     }
106                 }
107             }
108         }
109         
110         if( finded ) printf("YES\n");
111         else printf("NO\n");
112     }
113     
114     return 0;
115 }