hdu 1512

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=0;i<Maxn;i++){
        sz[i]=1;
        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 0;
    int s1,s2;
    s1=q[x].top();
    s2=q[y].top();
    q[x].pop();
    q[y].pop();
    s1/=2;
    s2/=2;
    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 1;
}
int main()
{
    int n,m,i,j;
    while(scanf("%d",&n)!=EOF){
        init();
        for(i=0;i<Maxn;i++){
            while(!q[i].empty())
                q[i].pop();
        }
        int val;
        for(i=1;i<=n;i++){
            scanf("%d",&val);
            q[i].push(val);
        }
        scanf("%d",&m);
        int a,b;
        for(i=1;i<=m;i++){
            scanf("%d%d",&a,&b);
            if(!merg(a,b))
                printf("-1\n");
        }
    }
    return 0;
}