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;

}