【luogu P1456 Monkey King】 题解

题目链接：https://www.luogu.org/problemnew/show/P1456
左偏树并查集不加路径压缩吧...

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int maxn = 100000 + 10;
struct Left_Tree{
    int val, fa, son[2], dis;
}h[maxn<<2];
int n, m;
int Merge(int r1, int r2)
{
    if(r1 == 0 || r2 == 0) return r1 + r2;
    if(h[r1].val < h[r2].val) swap(r1, r2);
    h[r1].son[1] = Merge(h[r1].son[1], r2);
    h[h[r1].son[1]].fa = r1;
    if(h[h[r1].son[0]].dis < h[h[r1].son[1]].dis) swap(h[r1].son[1], h[r1].son[0]);
    if(h[r1].son[1] == 0) h[r1].dis = 0;
    else h[r1].dis = h[h[r1].son[1]].dis + 1;
    return r1;
}
int destory(int r1)
{ 
    int le = h[r1].son[0], ri = h[r1].son[1];
    h[le].fa = 0;h[ri].fa = 0;
    int res = Merge(le, ri);
    h[r1].son[0] = h[r1].son[1] = 0;
    return res;
}
int find(int x)
{
    while(h[x].fa)
    x = h[x].fa;
    return x;
}
int main()
{
    while(scanf("%d",&n) != EOF)
    {
        for(int i = 1; i <= n; i++)
        {
            h[i].val = h[i].fa = 0;
            h[i].son[0] = h[i].son[1] = h[i].dis = 0;
        }
        for(int i = 1; i <= n; i++)
        scanf("%d",&h[i].val);
        
        scanf("%d",&m);
        for(int i = 1; i <= m; i++)
        {
            int opt, x, y;
            scanf("%d%d",&x,&y);
            int t1 = find(x), t2 = find(y);
            if(t1 == t2) 
            {
                printf("-1\n");
                continue;	
            }
                h[t1].val /= 2; h[t2].val /= 2;
                int left = destory(t1);
                int right = destory(t2);
                left = Merge(left, t1);
                right = Merge(right, t2);
                left = Merge(left, right);
                printf("%d\n",h[left].val);
        }
    }
    return 0;
}