【HDOJ】1072 Nightmare

bfs，使用ttl进行剪枝。

 #include <iostream>
 #include <cstdio>
 #include <cstring>
 #include <queue>
 using namespace std;

 #define MAXNUM 10

 int map[MAXNUM][MAXNUM], ttls[MAXNUM][MAXNUM], n, m;
 int direct[][] = {{-,},{,},{,-},{,}};

 typedef struct node_st {
     int ttl;
     int t;
     int x, y;
     node_st() {}
     node_st(int ttll, int tt, int xx, int yy) {
         ttl = ttll;
         t = tt;
         x = xx;
         y = yy;
     }
 } node_st;

 int bfs(int begx, int begy) {
     int val = -;
     int x=begx, y=begy, ttl=, t=;
     int newx, newy, newt, newttl;
     queue<node_st> nodes;
     node_st node;

     memset(ttls, , sizeof(ttls));
     nodes.push(node_st(ttl,t,x,y));
     map[x][y] = ;

     while ( !nodes.empty() ) {
         node = nodes.front();
         nodes.pop();
         x = node.x;
         y = node.y;
         ttl = node.ttl;
         t = node.t;
         if (map[x][y]== && ttl) {
             val = node.t;
             break;
         }
         --ttl; ++t;
         if (ttl == )
             continue;
         for (int i=; i<; ++i) {
             newx = x + direct[i][];
             newy = y + direct[i][];
             newttl = ttl;
             newt = t;
             if (newx< || newx>=n || newy< || newy>=m)
                 continue;
             if (map[newx][newy] == )
                 continue;
             if (map[newx][newy] == ) {
                 newttl = ;
                 map[newx][newy] = ;
             }
             if (newttl > ttls[newx][newy]) {
                 ttls[newx][newy] = newttl;
                 nodes.push(node_st(newttl, newt, newx, newy));
             }
         }
     }

     return val;
 }

 int main() {
     int t;
     int i, j, begx, begy;

     scanf("%d", &t);

     while (t--) {
         scanf("%d %d", &n, &m);
         for (i=; i<n; ++i) {
             for (j=; j<m; ++j) {
                 scanf("%d", &map[i][j]);
                 if (map[i][j] == ) {
                     begx = i;
                     begy = j;
                 }
             }
         }
         i = bfs(begx, begy);
         printf("%d\n", i);
     }

     return ;
 }