【HDOJ】2757 Ocean Currents

简单BFS。

 /* 2757 */
 #include <iostream>
 #include <queue>
 #include <cstdio>
 #include <cstring>
 #include <cstdlib>
 using namespace std;

 #define MAXN 1005

 typedef struct node_t {
     int k, t;
     node_t() {}
     node_t(int kk, int tt) {
         k = kk; t = tt;
     }
     friend bool operator <(const node_t &a, const node_t &b) {
         return a.t > b.t;
     }
 } node_t;

 int n, m;
 int bx, by, ex, ey;
 char map[MAXN][MAXN];
 int visit[MAXN][MAXN];
 int dir[][] = {
     -,, -,, ,, ,,
     ,, ,-, ,-, -,-
 };

 inline bool check(int x, int y) {
     return x< || x>=n || y<= || y>=m;
 }

 int bfs() {
     int xx, yy;
     int x, y, t;
     int i, j, k;
     node_t nd;
     priority_queue<node_t> Q;

     memset(visit, 0x3f, sizeof(visit));
     visit[bx][by] = ;
     nd.t = ;
     nd.k = bx*+by;
     Q.push(nd);

     while (!Q.empty()) {
         nd = Q.top();
         xx = nd.k/;
         yy = nd.k%;
         if (xx==ex && yy==ey)
             return nd.t;
         Q.pop();
         for (i=; i<; ++i) {
             x = xx + dir[i][];
             y = yy + dir[i][];
             if (check(x, y))
                 continue;
             if (map[xx][yy] == i)
                 t = nd.t;
             else
                 t = nd.t + ;
             if (visit[x][y] > t) {
                 visit[x][y] = t;
                 k = *x+y;
                 Q.push(node_t(k, t));
             }
         }
     }

     return ;
 }

 int main() {
     int i, j, k;
     int t;

     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
         freopen("data.out", "w", stdout);
     #endif

     while (scanf("%d%d",&n,&m) != EOF) {
         for(i=; i<n; ++i) {
             scanf("%s", map[i]);
             for (j=; j<m; ++j)
                 map[i][j] -= '';
         }
         scanf("%d", &t);
         while (t--) {
             scanf("%d%d%d%d",&bx,&by,&ex,&ey);
             --bx; --by; --ex; --ey;
             if (bx==ex && by==ey)
                 k = ;
             else
                 k = bfs();
             printf("%d\n", k);
         }
     }

     return ;
 }