rt 代码：

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<queue>
#define PII pair<int,int>
#define mp make_pair
#define int long long
using namespace std;
typedef long long ll;
const int N=5e3+5;
const int M=2e4+5;
const int T=1e7+5;
const int INF=1e18;
struct Edge{
    int v,w,next;
}edge[M];
struct Weight{
    int ans,u,v;
}res[T];
int n,m,k,tot=0,amt=0,ans=-INF;
int head[M],val[M],g[N][N];
inline void add(int u,int v,int w){
    edge[++tot]=(Edge){v,w,head[u]},head[u]=tot;
}
inline int read(){
    int s=0,f=1;char ch=getchar();
    while (!isdigit(ch)) {if (ch=='-'){f=-1;} ch=getchar();}
    while (isdigit(ch)) {s=(s<<1)+(s<<3)+ch-'0'; ch=getchar();}
    return s*f;
}
inline void dijkstra(int s)
{
    int d[N],vis[N];
    memset(d,0x3f,sizeof(d));
    memset(vis,0,sizeof(vis));
    queue <int> q;d[s]=0;q.push(s);
    while (!q.empty())
    {
        int u=q.front();q.pop();
        if (vis[u]) continue;
        vis[u]=true;
        for (int i=head[u];i;i=edge[i].next)
        {
            int v=edge[i].v,w=edge[i].w;
            if (d[v]>d[u]+w)
            {
                d[v]=d[u]+w;
                q.push(v);
            }
        }
    }
    for (int i=1;i<=n;i++)
        g[s][i]=d[i];
}
inline bool comp(Weight x,Weight y){
    return x.ans>y.ans;
}
signed main()
{
    freopen("holiday.in","r",stdin);
    freopen("holiday.out","w",stdout);
    n=read(),m=read(),k=read();
    for (int i=2;i<=n;i++) val[i]=read();
    for (int i=1;i<=m;i++)
    {
        int u=read(),v=read();
        add(u,v,1),add(v,u,1);
    }
    for (int i=1;i<=n;i++) dijkstra(i);
    for (int i=2;i<=n;i++)
    {
        int u=i;
        if (g[1][u]>k+1) continue;
        for (int j=2;j<=n;j++)
        {
            if (j==u) continue;
            int v=j;
            if (g[u][v]>k+1) continue;
            res[++amt]=(Weight){val[u]+val[v],u,v};
        }
    }
    sort(res+1,res+1+amt,comp);
    int l=0,r=0;
    while (l<=amt)
    {
        l++;
        while (r<=amt)
        {
            r++;
            if (res[l].u==res[r].u || res[l].u==res[r].v) continue;
            if (res[l].v==res[r].u || res[l].v==res[r].v) continue;
            if (g[res[l].v][res[r].v]<=k+1)
            {
                int tmp=res[l].ans+res[r].ans;
                ans=max(ans,tmp);
            }
        }
    }
    printf("%lld",ans);
    fclose(stdin);
    fclose(stdout);
    return 0;
}