总共跑了500多ms，领先第二名的左偏树和第三名的线段树合并(我没看错吧)200多ms。

#include<bits/stdc++.h>
using namespace std;
#define re register
const int N=1e5+5;
const int M=5e5+5;
int n,m,k,a[N],f[N],sz[N],ans[M];
vector<int> g[N]; 
inline int find(int x){
	return f[x]==x?x:f[x]=find(f[x]);
}
struct xx{
	int u,v,w;
}e[M];
struct xx2{
	int u,k,w,id;
}q[M];
bool cmp(xx ax,xx ay){
	return ax.w<ay.w;
}
bool cmp2(xx2 ax,xx2 ay){
	return ax.w<ay.w;
}
#define gc getchar_unlocked
inline int rd() {
	int x = 0; char ch = gc();
	while(ch < '0' || ch > '9') ch = gc();
	while(ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = gc();
	return x;
}
int main(){
	n=rd(),m=rd(),k=rd();
	for(re int i=1;i<=n;i++){
		a[i]=rd();
		f[i]=i,sz[i]=1,g[i].push_back(a[i]);
	}
	for(re int i=1;i<=m;i++) e[i].u=rd(),e[i].v=rd(),e[i].w=rd();
	sort(e+1,e+m+1,cmp);
	for(re int i=1;i<=k;i++){
		q[i].u=rd(),q[i].w=rd(),q[i].k=rd();
		q[i].id=i;
	}
	sort(q+1,q+k+1,cmp2);
	int cnt=1;
	for(re int i=1;i<=k;i++){
		//printf("111 %d\n",i);
		while(q[i].w>=e[cnt].w&&cnt<=m){
			//printf("222 %d\n",cnt);
			int fx=find(e[cnt].u),fy=find(e[cnt].v);
			if(fx==fy){
				cnt++;
				continue;
			}
			int sx=sz[fx],sy=sz[fy];
			if(sx==0||sy==0){
				cnt++;
				continue;
			}
			if(sx>sy) swap(sx,sy),swap(fx,fy);
			f[fx]=fy;
			sz[fy]+=sz[fx];
			if(sx<=sqrt(sy)){
				while(sx--){
					int now=g[fx].back();
					g[fy].insert(lower_bound(g[fy].begin(),g[fy].end(),now),now);
					g[fx].pop_back();
				}
			}else{
				while(sx--){
					g[fy].push_back(g[fx].back());
					g[fx].pop_back();
				}
				stable_sort(g[fy].begin(),g[fy].end());
			}
			cnt++;
		}
		int fx=find(q[i].u);
		if(q[i].k>sz[fx]) ans[q[i].id]=-1;
		else ans[q[i].id]=g[fx][sz[fx]-q[i].k];
	}
	for(re int i=1;i<=k;i++) printf("%d\n",ans[i]);
	return 0;
}