蒟蒻27分 求大佬帮忙看一下QAQ 主要是dijkstra+二分QAQ

#include<bits/stdc++.h>
#define For(i,m,n) for(register int i=m;i<n;i++)
#define rFor(i,m,n) for(register int i=m;i>n;i--)
#define r(a) read(a)
#define rr(a,b) read(a),read(b)
#define rrr(a,b,c) read(a),read(b),read(c)
using namespace std;
typedef long long ll;
typedef unsigned long long Ull;
template <class T>
inline void read(T &x)
{
    x=0;
    T f=1;
    char ch=getchar();
    while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}
    while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
    x=x*f;
}
const int MaxN = 50010, MaxM = 100100;
const int INF=1e9;
struct edge{
    int next;
    int to;
    ll dis;
}e[MaxM];
int head[MaxN];
ll res[MaxN];
int tot=0;
bool vis[MaxM];
int n,m,s;
ll b;
ll fi[MaxN];
ll start,ed;
void add_edge(int from,int to,ll dis)
{
    tot++;
    e[tot].next=head[from];
    e[tot].to=to;
    e[tot].dis=dis;
    head[from]=tot;
}

priority_queue<int,vector<int>,greater<int> > Q;

bool dijkstra(ll mid)
{
    if(mid<start)    return true;
    For(i,1,n+1)   res[i]=INF;
    memset(vis,0,sizeof(vis));
    res[s]=0;
    Q.push(s);//保证从开始结点出发不断更新
    while(Q.size()){
        int x=Q.top();
        Q.pop();
        if(vis[x])    continue;
        vis[x]=1;
        for(int i=head[x];i;i=e[i].next){
            int v=e[i].to;
            if(fi[v]>mid)  continue;
            if(res[v]>res[x]+e[i].dis)
                res[v]=res[x]+e[i].dis;
            if(!vis[v])   Q.push(v);//保证了从起始节点往下走
        }
    }
    return res[n]>=b;
}

int main()
{
    rrr(n,m,b);
    For(i,1,n+1)    r(fi[i]);
    start=fi[1];
    s=1;
    sort(fi+1,fi+1+n);
    For(i,1,m+1){
        ll u,v,d;
        rrr(u,v,d);
        add_edge(u,v,d);
        add_edge(v,u,d);
    }

    if(dijkstra(fi[n])){
        cout<<"AFK";
        return 0;
    }
    ll lo,hi;
    lo=1,hi=n+1;
    while(lo<hi){
        ll mid=(lo+hi)/2;
        if(dijkstra(fi[mid])){
            lo=mid+1;
        }
        else{
            hi=mid;
        }
    }
    cout<<fi[lo];
    return 0;
}