uva oj 567 - Risk(Floyd算法)

 /*
 一张有20个顶点的图上。
 依次输入每个点与哪些点直接相连。
 并且多次询问两点间，最短需要经过几条路才能从一点到达另一点。

 bfs 水过
 */
 #include<iostream>
 #include<cstring>
 #include<vector>
 #include<cstdio>
 #include<queue>
 using namespace std;

 struct node{
    int x, step;
    node(){

    }
    node(int x, int step){
       this->x=x;
       this->step=step;
    }
 }; 

 vector<int>v[];
 queue<node>q;
 int vis[];

 int b, e;

 void bfs(){
    while(!q.empty())  q.pop();
    node cur;
    q.push(node(b, ));
    while(!q.empty()){
        cur=q.front();
        q.pop();
        if(cur.x==e){
            printf("%2d to %2d: %d\n", b, e, cur.step);
            return;
        }
        int len=v[cur.x].size();
        for(int i=; i<len; ++i){
              if(v[cur.x][i]==e){
              printf("%2d to %2d: %d\n", b, e, cur.step+);
              return;
           }
           if(!vis[v[cur.x][i]]){
                vis[v[cur.x][i]]=;
              q.push(node(v[cur.x][i], cur.step+));
           }
        }
    }
 }

 int main(){
     int n, u;
     int cnt=;
     while(scanf("%d", &n)!=EOF){
         while(n--){
            scanf("%d", &u);
            v[].push_back(u);
            v[u].push_back();
         }
         for(int i=; i<=; ++i){
            scanf("%d", &n);
            while(n--){
               scanf("%d", &u);
               v[i].push_back(u);
               v[u].push_back(i);
            }
         }
         scanf("%d", &n);
         printf("Test Set #%d\n", ++cnt);
         while(n--){
            scanf("%d%d", &b, &e) ;
            bfs();
            memset(vis, , sizeof(vis));
         }
         printf("\n");
         for(int i=; i<=; ++i)
            v[i].clear();

     }
     return ;
 }

 /*
    Floyd 才是正解！
 */
 #include<iostream>
 #include<cstring>
 #include<vector>
 #include<cstdio>
 #include<queue>
 #define INF 0x3f3f3f3f
 using namespace std;

 int map[][];

 void Folyd(){
    for(int k=; k<=; ++k)
       for(int i=; i<=; ++i)
          for(int j=; j<=; ++j)
             if(map[i][j] > map[i][k] + map[k][j])
                map[i][j] = map[i][k] + map[k][j];
 }

 int main(){
     int n, u, b, e;
     int cnt=;
     while(scanf("%d", &n)!=EOF){
         memset(map, 0x3f, sizeof(map));
         while(n--){
            scanf("%d", &u);
            map[][u]=map[u][]=;
         }
         for(int i=; i<=; ++i){
            scanf("%d", &n);
            while(n--){
               scanf("%d", &u);
               map[u][i]=map[i][u]=;
            }
         }
         scanf("%d", &n);
         printf("Test Set #%d\n", ++cnt);
         Folyd();
         while(n--){
            scanf("%d%d", &b, &e) ;
            printf("%2d to %2d: %d\n", b, e, map[b][e]);
         }
         printf("\n");
     }
 }