luogu_1462 通往奥格瑞玛的道路

#include <iostream>
#include <cstdio>
#include <queue>
#include <algorithm>
#include <cstring>
using namespace std;
const int maxn=10010;
const int maxm=50010;
const int INF=1<<30;
struct edge{int v,b;};
int n,m,b,cost[maxn],d[maxn],s=1,t,ans;
bool vis[maxn];
vector<edge> G[maxm];
queue<int> q;

bool spfa(int x){
	memset(vis,0,sizeof(vis));
	for(int i=1;i<=n;i++)d[i]=INF;
	q.push(s); d[s]=0; vis[s]=1;
	if(cost[s]>x)return false;
	while(!q.empty()){
		int u=q.front(); q.pop(); vis[u]=0;
		for(int i=0;i<G[u].size();i++){
			int v=G[u][i].v,rd=G[u][i].b;
			if(d[u]+rd<d[v] && d[u]+rd<=b && cost[v]<=x){
				d[v]=d[u]+rd;
				if(!vis[v]){q.push(v); vis[v]=1;}
			}
		}
	}
	return d[t]!=INF;
}

int main(){
	scanf("%d%d%d",&n,&m,&b);
	t=n;
	int l=0,r=0;
	for(int i=1;i<=n;i++){scanf("%d",&cost[i]); r=max(r,cost[i]);}
	while(m--){
		int u,v,b;
		scanf("%d%d%d",&u,&v,&b);
		G[u].push_back((edge){v,b}); G[v].push_back((edge){u,b});
	}

	while(l<=r){
		int mid=(l+r)/2;
		if(spfa(mid)){
			ans=mid;
			r=mid-1;
		}
		else l=mid+1;
	}
	if(!ans)puts("AFK");
	else printf("%d\n",ans);
	return 0;
}