思路：用并查集即可，每次合并的时候将小的集合合并到大的集合上去。理论上的平均复杂度是n*lgn*lgn。
#include<map>
#include<queue>
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#define Maxn 100010
#define LL long long
#define Mod 1000000007
int sz[Maxn],fa[Maxn];
using namespace std;
priority_queue<int> q[Maxn];
void init()
{
for(int i=;i<Maxn;i++){
sz[i]=;
fa[i]=i;
}
}
int find(int x)
{
if(x!=fa[x])
fa[x]=find(fa[x]);
return fa[x];
}
int merg(int a,int b)
{
int x=find(a);
int y=find(b);
if(x==y) return ;
int s1,s2;
s1=q[x].top();
s2=q[y].top();
q[x].pop();
q[y].pop();
s1/=;
s2/=;
if(sz[x]>sz[y]){
q[x].push(s1);
q[x].push(s2);
while(!q[y].empty()){
q[x].push(q[y].top());
q[y].pop();
}
printf("%d\n",q[x].top());
sz[x]+=sz[y];
fa[y]=x;
}else{
q[y].push(s1);
q[y].push(s2);
while(!q[x].empty()){
q[y].push(q[x].top());
q[x].pop();
}
printf("%d\n",q[y].top());
sz[y]+=sz[x];
fa[x]=y;
}
return ;
}
int main()
{
int n,m,i,j;
while(scanf("%d",&n)!=EOF){
init();
for(i=;i<Maxn;i++){
while(!q[i].empty())
q[i].pop();
}
int val;
for(i=;i<=n;i++){
scanf("%d",&val);
q[i].push(val);
}
scanf("%d",&m);
int a,b;
for(i=;i<=m;i++){
scanf("%d%d",&a,&b);
if(!merg(a,b))
printf("-1\n");
}
}
return ;
}