hdu 1512 并查集

又是基于连通性的问题，可以用并查集来解决，每个集合都维护一个优先队列，合并的时候按照优先队列的大小启发式合并即可。

#include <iostream>
#include <cstring>
#include <cstdio>
#include <queue>
using namespace std;

const int N = 100001;
int f[N];
priority_queue<int> q[N];
int n, m;

void init()
{
    for ( int i = 1; i <= n; i++ )
    {
        f[i] = i;
        while ( !q[i].empty() ) q[i].pop();
    }
}

int findf( int x )
{
    if ( f[x] != x ) f[x] = findf( f[x] );
    return f[x];
}

int union_set( int x, int y )
{
    x = findf(x), y = findf(y);
    if ( x == y ) return -1;
    int sx = q[x].top();
    q[x].pop();
    sx >>= 1;
    int sy = q[y].top();
    q[y].pop();
    sy >>= 1;
    if ( q[x].size() > q[y].size() ) swap( x, y );
    f[x] = y;
    while ( !q[x].empty() )
    {
        int nn = q[x].top();
        q[x].pop();
        q[y].push(nn);
    }
    q[y].push(sx);
    q[y].push(sy);
    return q[y].top();
}

int main ()
{
    while ( scanf("%d", &n) != EOF )
    {
        init();
        for ( int i = 1; i <= n; i++ )
        {
            int tmp;
            scanf("%d", &tmp);
            q[i].push(tmp);
        }
        scanf("%d", &m);
        while ( m-- )
        {
            int u, v;
            scanf("%d%d", &u, &v);
            printf("%d
", union_set( u, v ));
        }
    }
    return 0;
}