萌新WA两个点求助

#include<bits/stdc++.h>
using namespace std;
int n,m,s,e;
int ver[6300],edge[6300],head[2600],next[6300],tot=0; 
int d[2600];
priority_queue< pair<int,int> > q;
bool vis[2600];
void add(int a,int b,int c){
	ver[++tot]=b,edge[tot]=c,next[tot]=head[a],head[a]=tot;
	return;
}
void dijstra(){
	memset(vis,0,sizeof(vis));
	memset(d,0x3f,sizeof(d));
	d[s]=0;
	q.push(make_pair(0,s));
	while(q.size()){
		int x=q.top().second;q.pop();
		if(vis[x]) continue;
		vis[x]=1;
		for(int i=head[x];i!=0;i=next[i]){
			int y=ver[i],z=edge[i];
			if(d[y]>d[x]+z){
				d[y]=d[x]+z;
				q.push(make_pair(-d[y],y)); 
			} 
		}
	}
	return;
}
int main(){
	scanf("%d%d%d%d",&n,&m,&s,&e);
	for(int i=1;i<=m;++i){
		int t1,t2,t3;
		scanf("%d%d%d",&t1,&t2,&t3);
		add(t1,t2,t3),add(t2,t1,t3);
	}
	dijstra();
	printf("%d\n",d[e]);
	return 0;
}