对于这类需要钥匙才能通过的迷宫来说，一般visit数组会开成三维的：bool visit[N][N][1 << 10];最后一维表示通过该位置时的拥有的钥匙的情况。
1 #include <iostream> 2 #include <cstring> 3 #include <cstdio> 4 #include <cctype> 5 #include <queue> 6 using namespace std; 7 8 const int N = 21; 9 char maze[N][N]; 10 bool visit[N][N][1 << 10]; 11 int dx[] = { 0, 0, 1, -1 }; 12 int dy[] = { 1, -1, 0, 0 }; 13 int sx, sy, ex, ey; 14 int n, m, t; 15 16 bool ok( int x, int y ) 17 { 18 return x >= 0 && x < n && y >= 0 && y < m; 19 } 20 21 struct Node 22 { 23 int x, y, step, state; 24 Node(){} 25 Node( int _x, int _y, int _step, int _state ) 26 { 27 x = _x, y = _y, step = _step, state = _state; 28 } 29 }; 30 31 queue<Node> q; 32 33 int bfs() 34 { 35 while ( !q.empty() ) q.pop(); 36 memset( visit, false, sizeof(visit) ); 37 q.push( Node( sx, sy, 0, 0 ) ); 38 visit[sx][sy][0] = true; 39 while ( !q.empty() ) 40 { 41 Node cur = q.front(); 42 q.pop(); 43 if ( cur.step == t ) return -1; 44 if ( cur.x == ex && cur.y == ey ) return cur.step; 45 for ( int i = 0; i < 4; i++ ) 46 { 47 int xx = cur.x + dx[i]; 48 int yy = cur.y + dy[i]; 49 if ( ok( xx, yy ) ) 50 { 51 if ( maze[xx][yy] == '*' ) continue; 52 if ( isupper( maze[xx][yy] ) ) 53 { 54 int tmp = ( 1 << ( maze[xx][yy] - 'A' ) ); 55 if ( ( cur.state & tmp ) && !visit[xx][yy][cur.state] ) 56 { 57 q.push( Node( xx, yy, cur.step + 1, cur.state) ); 58 visit[xx][yy][cur.state] = true; 59 } 60 } 61 else if ( islower( maze[xx][yy] ) ) 62 { 63 int tmp = ( 1 << ( maze[xx][yy] - 'a' ) ); 64 if ( !visit[xx][yy][cur.state | tmp] ) 65 { 66 q.push( Node( xx, yy, cur.step + 1, cur.state | tmp ) ); 67 visit[xx][yy][cur.state | tmp] = true; 68 } 69 } 70 else 71 { 72 if ( !visit[xx][yy][cur.state] ) 73 { 74 q.push( Node( xx, yy, cur.step + 1, cur.state ) ); 75 visit[xx][yy][cur.state] = true; 76 } 77 } 78 } 79 } 80 } 81 return -1; 82 } 83 84 int main () 85 { 86 while ( scanf("%d%d%d", &n, &m, &t) != EOF ) 87 { 88 for ( int i = 0; i < n; i++ ) 89 { 90 scanf("%s", maze[i]); 91 for ( int j = 0; j < m; j++ ) 92 { 93 if ( maze[i][j] == '@' ) 94 { 95 sx = i; 96 sy = j; 97 maze[i][j] = '.'; 98 } 99 else if ( maze[i][j] == '^' ) 100 { 101 ex = i; 102 ey = j; 103 maze[i][j] = '.'; 104 } 105 } 106 } 107 int ans = bfs(); 108 printf("%d ", ans); 109 } 110 return 0; 111 }