zoj2750最短路

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <climits>
#include <string>
#include <iostream>
#include <map>
#include <cstdlib>
#include <list>
#include <set>
#include <queue>
#include <stack>

using namespace std;
const int INF=1000000000;

struct Node
{
    int x;int val;
};
struct cmp
{
    bool operator () (const Node &a,const Node &b)
    {
        return a.val>b.val;
    }
};
int n;
const int maxn=1111;
int dis[maxn];
int vis[maxn];
int Map[maxn][maxn];
void djs(int x)
{
    for(int i=0;i<n;i++){
        dis[i]=INF;
    }
    memset(vis,0,sizeof(vis));
    dis[x]=0;vis[x]=1;
    Node k; k.x=x;k.val=0;
    priority_queue < Node ,vector<Node> ,cmp> q;
    q.push(k);
    while(!q.empty()){
        Node k=q.top();q.pop();
        int cur=k.x;vis[cur]=1;
        for(int i=0;i<n;i++){
            if(dis[i]>dis[cur]+Map[cur][i]){
                dis[i]=dis[cur]+Map[cur][i];
                if(!vis[i]){
                    Node k; k.x=i;k.val=dis[i]; q.push(k);
                }
            }
        }
    }
}
int main()
{
   string b,beh[10000],pre[10000];
    int val[10000];
    while(cin>>n,n){
        for(int i=0;i<n;i++)
        for(int j=0;j<n;j++)
        Map[i][j]=INF;
        for(int i=0;i<n;i++){
             int a;string b;cin>>a>>b;int len=b.length();
             val[i]=a;pre[i]=b.substr(0,4);beh[i]=b.substr(len-4,4);
        }
      //  for(int i=0;i<n;i++)
           // cout<<val[i]<<" "<<pre[i]<<" "<<beh[i]<<endl;
        for(int i=0;i<n;i++){
            for(int j=0;j<n;j++){
                if(i==j) continue;
                if(beh[i]==pre[j]){
                    if(val[i]<Map[i][j])
                    Map[i][j]=val[i];//printf("%d %d %d",i,j,val[i]);system("pause");
                }
            }
        }
        djs(0);
        if(dis[n-1]==INF)
            cout<<-1<<endl;
        else cout<<dis[n-1]<<endl;
    }
    return 0;
}