UVa 10653 - Bombs! NO they are Mines!!

　　题目大意：给你一个二维迷宫，给定入口和出口，找出最短路径。

　　无权图上的单源最短路，用BFS解决。

 #include <cstdio>
 #include <queue>
 #include <cstring>
 using namespace std;
 #define MAXN 1100

 int G[MAXN][MAXN], dist[MAXN*MAXN];
 const int dir[][] = {{-, }, {, -}, {, }, {, }};

 int main()
 {
 #ifdef LOCAL
     freopen("in", "r", stdin);
 #endif
     int R, C;
     while (scanf("%d%d", &R, &C) && (R || C))
     {
         int k;
         scanf("%d", &k);
         memset(G, , sizeof G);
         for (int i = ; i < k; i++)
         {
             int r, n;
             scanf("%d%d", &r, &n);
             for (int j = ; j < n; j++)
             {
                 int x;
                 scanf("%d", &x);
                 G[r][x] = ;
             }
         }
         int x, y;
         scanf("%d%d", &x, &y);
         int src = x*C + y;
         scanf("%d%d", &x, &y);
         int dest = x*C + y;
         queue<int> q;
         memset(dist, -, sizeof dist);
         q.push(src);
         dist[src] = ;
         while (!q.empty())
         {
             int u = q.front();
             q.pop();
             if (u == dest)  break;
             int x = u / C;
             int y = u % C;
             for (int i = ; i < ; i++)
             {
                 int dx = x + dir[i][], dy = y + dir[i][];
                 int v = dx * C + dy;
                 if (dx >=  && dx < R && dy >=  && dy < C && G[dx][dy] ==  && dist[v] == -)
                 {
                     dist[v] = dist[u] + ;
                     q.push(v);
                 }
             }
         }
         printf("%d\n", dist[dest]);
     }
     return ;
 }