求助

#include<bits/stdc++.h>
using namespace std;
int n,m,s,head[500005],cnt,to[500005],nex[500005],w[500005],dis[100005],vis[100005];
struct node{
    int pos,dis;
    bool operator < (const node &x) const{
        x.dis<dis;
    }
};
void add(int x,int y,int d)
{
    to[++cnt]=y;
    w[cnt]=d;
    nex[cnt]=head[x]; 
    head[x]=cnt;
}
priority_queue<node> a;
int main()
{
     cin>>n>>m>>s;
     for(int i=1;i<=n;i++)
       dis[i]=INT_MAX;
     for(int i=1;i<=m;i++)
     {
        int x,y,d;
        cin>>x>>y>>d;
        add(x,y,d);
     }
     a.push( ( node ){s,0 } );
     dis[s]=0;
     while(!a.empty())
     {
        int t,tt;
        node q=a.top();
        a.pop();
        t=q.pos;tt=q.dis;
        if(vis[t])
          continue;
        vis[t]=1;
        for(int i=head[t];i;i=nex[i])
        {
            if(dis[to[i]]>w[i]+tt)
            {
                dis[to[i]]=w[i]+tt;

            }
             a.push((node){to[i],dis[to[i]]});

        }
     }
     for(int i=1;i<=n;i++)
     {
        cout<<dis[i]<<" ";
     }
}