用的map映射爲整數，後面就和普通的最短路一樣的，注意頭文件。
#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<stack>
#include<queue>
#include<map>
using namespace std;
#define inf 10000000
int a[505][505],book[505],dis[505];
int n,m;
char b[35],c[35];
int flag;
void init()
{
n=0;
flag=0;
memset(book,0,sizeof(book));
for(int i=0;i<=155;i++){
for(int j=0;j<=155;j++){
a[i][j]=inf;
}
}
map<string,int>station;
station.clear();
scanf("%s%s",b,c);
if(strcmp(b,c)==0){flag=1;}
station[b]=1;
station[c]=2;
n=2;
int dd;
for(int i=1;i<=m;i++){
scanf("%s%s%d",b,c,&dd);
if(!station[b]){
station[b]=++n;
//cout<<station[b]<<endl;
}
if(!station[c]){
station[c]=++n;
//cout<<station[c]<<endl;
}
a[station[b]][station[c]]=a[station[c]][station[b]]=dd;
}
}
void dij()
{
for(int i=1;i<=n;i++){
dis[i]=a[1][i];
}
book[1]=1;
for(int i=1;i<=n-1;i++){
int u=0,mmin=inf;
for(int j=1;j<=n;j++){
if(book[j]==0&&dis[j]<mmin){
mmin=dis[j];
u=j;
}
}
book[u]=1;
for(int k=1;k<=n;k++){
if(!book[k]&&dis[k]>dis[u]+a[u][k]){
dis[k]=dis[u]+a[u][k];
}
}
}
}
int main()
{
while(scanf("%d",&m)!=EOF)
{
if(m==-1){return 0;}
init();
dij();
if(flag==1){printf("0\n");}
else {
if(dis[2]<inf){
printf("%d\n",dis[2]);}
else {
printf("-1\n");
}
}
}
}