BFS HDOJ 1728 逃离迷宫

  1 /*
  2     BFS：三维BFS，加上方向。用dp[x][y][d]记录当前需要的最少转向数
  3 */
  4 #include <cstdio>
  5 #include <algorithm>
  6 #include <cstring>
  7 #include <queue>
  8 #include <cmath>
  9 using namespace std;
 10 
 11 const int MAXN = 1e2 + 10;
 12 const int INF = 0x3f3f3f3f;
 13 struct P
 14 {
 15     int x, y, z;
 16 }now, to;
 17 char maze[MAXN][MAXN];
 18 int dp[MAXN][MAXN][4];
 19 bool inq[MAXN][MAXN][4];
 20 int dx[4] = {-1, 1, 0, 0};
 21 int dy[4] = {0, 0, -1, 1};
 22 int k, x1, y1, x2, y2;
 23 int n, m;
 24 
 25 bool check(int x, int y)
 26 {
 27     if (x >= 1 && x <= n && y >= 1 && y <= m)    return true;
 28     else    return false;
 29 }
 30 
 31 bool BFS(void)
 32 {
 33     memset (dp, 0, sizeof (dp));
 34     memset (inq, false, sizeof (inq));
 35     queue<P> Q;
 36     for (int i=1; i<=n; ++i)
 37     {
 38         for (int j=1; j<=m; ++j)
 39         {
 40             for (int l=0; l<4; ++l)
 41             {
 42                 dp[i][j][l] = INF;    inq[i][j][l] = false;
 43             }
 44         }
 45     }
 46     for (int i=0; i<4; ++i)
 47     {
 48         dp[x1][y1][i] = 0;    inq[x1][y1][i] = true;
 49         Q.push ((P) {x1, y1, i});
 50     }
 51 
 52     while (!Q.empty ())
 53     {
 54         now = Q.front ();    Q.pop ();
 55         for (int i=0; i<4; ++i)
 56         {
 57             to.x = now.x + dx[i];
 58             to.y = now.y + dy[i];    to.z = i;
 59             if (check (to.x, to.y) && maze[to.x][to.y] == '.')
 60             {
 61                 int tmp = dp[now.x][now.y][now.z];
 62                 if (to.z == now.z)
 63                 {
 64                     if (tmp < dp[to.x][to.y][to.z])
 65                     {
 66                         dp[to.x][to.y][to.z] = tmp;
 67                         if (!inq[to.x][to.y][to.z])
 68                         {
 69                             inq[to.x][to.y][to.z] = true;    Q.push (to);
 70                         }
 71                     }
 72                 }
 73                 else
 74                 {
 75                     if (++tmp < dp[to.x][to.y][to.z])
 76                     {
 77                         dp[to.x][to.y][to.z] = tmp;
 78                         if (!inq[to.x][to.y][to.z])
 79                         {
 80                             inq[to.x][to.y][to.z] = true;    Q.push (to);
 81                         }
 82                     }
 83                 }
 84             }
 85         }
 86         inq[now.x][now.y][now.z] = false;
 87     }
 88 
 89     for (int i=0; i<4; ++i)
 90     {
 91         if (dp[x2][y2][i] <= k)    return true;
 92     }
 93 
 94     return false;
 95 }
 96 
 97 int main(void)        //HDOJ 1728 逃离迷宫
 98 {
 99 //    freopen ("HDOJ_1728.in", "r", stdin);
100 
101     int t;    scanf ("%d", &t);
102     while (t--)
103     {
104         scanf ("%d%d", &n, &m);
105         for (int i=1; i<=n; ++i)    scanf ("%s", maze[i] + 1);
106         scanf ("%d%d%d%d%d", &k, &y1, &x1, &y2, &x2);
107         if (BFS ())    puts ("yes");
108         else    puts ("no");
109     }
110 
111     return 0;
112 }
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