poj2387 最短路

#include<stdio.h>
#include<string.h>
#include<queue>
using namespace std;

int head[1005],dist[1005],next[4005],point[4005],val[4005],size;
bool vis[1005];

void add(int a,int b,int v){
int i;
for(i=head[a];~i;i=next[i]){
if(point[i]==b){
if(val[i]>v)val[i]=v;
return;
}
}
point[size]=b;
val[size]=v;
next[size]=head[a];
head[a]=size++;
}

void spfa(int s,int p){
memset(vis,0,sizeof(vis));
memset(dist,-1,sizeof(dist));
queue<int>q;
vis[s]=1;
dist[s]=0;
q.push(s);
while(!q.empty()){
int i,t=q.front();
vis[t]=0;
q.pop();
for(i=head[t];~i;i=next[i]){
int j=point[i];
if(dist[j]==-1||dist[j]>dist[t]+val[i]){
dist[j]=dist[t]+val[i];
if(!vis[j]){
q.push(j);
vis[j]=1;
}
}
}
}
printf("%d\n",dist[p]);
}

int main(){
int t,n;
while(scanf("%d%d",&t,&n)!=EOF){
int i,j;
memset(head,-1,sizeof(head));
size=0;
for(i=1;i<=t;i++){
int a,b,v;
scanf("%d%d%d",&a,&b,&v);
add(a,b,v);
add(b,a,v);
}
spfa(n,1);
}
return 0;
}