luogu 【P3377】 【模板】左偏树

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <cctype>
#include <iostream>
#define For(i, l, r) for(int i = (l); i <= (int)(r); ++i)
#define Fordown(i, r, l) for(int i = (r); i >= (int)(l); --i)
#define Set(a, v) memset(a, v, sizeof(a))
using namespace std;

inline int read(){
  int x = 0, fh = 1; char ch;
  for(; !isdigit(ch); ch = getchar()) if (ch == ‘-‘) fh = -1;
  for(; isdigit(ch); ch = getchar()) x = (x<<1) + (x<<3) + (ch^‘0‘);
  return x * fh;
}

struct node {
	int lc, rc, val;  //分别是left_child左儿子, right_child右儿子, value 键值
};
const int max_node = 100100; //最大子节点个数
node lt[max_node]; //leftist_tree 左偏树
int dist[max_node], fa[max_node]; //左偏树距离dist:到最右叶子节点边的条数
//并查集父亲数组fa

void make_tree (int x) {
	lt[x].lc = lt[x].rc = dist[x] = 0; //清空它的左右儿子和距离（新建一个树）
}

int merge (int a, int b) {
	if (a == 0) return b; //a为空 返回b
	if (b == 0) return a; //b为空 返回a
	if (lt[a].val > lt[b].val) swap(a, b); //将根节点设为a（值较小的那个）
	lt[a].rc = merge(lt[a].rc, b); fa[lt[a].rc] = a; //将b合并到a的右子树上 并将右子树父亲设为a
	if (dist[lt[a].rc] > dist[lt[a].lc]) swap(lt[a].lc, lt[a].rc); //右子节点距离大于左子节点 不符合左偏树性质则交换左右子树
	if (lt[a].rc == 0) dist[a] = 0; //右子树为空 距离为0 即直接到自己
	else dist[a] = dist[lt[a].rc] + 1; //否则按照性质 距离为右子节点的距离+1
	return a; //返回a节点
}

int find (int x) {
	return fa[x] = fa[x] == x ? x : find(fa[x]); //并查集操作
}


int main(){
	int n = read(), m = read();
	For (i, 1, n) {
		lt[i].val = read();
		make_tree(i);
		fa[i] = i;
	}
	while (m--) {
		int opt = read();
		if (opt == 1) {
			int a = read(), b = read();
			int root_a = find(a), root_b = find(b);
			if (root_a == root_b) continue; //在同一个堆里就不合并
			if (lt[a].val == 0 || lt[b].val == 0) continue; //这个数已被删掉也不合并
		//	cout << "merge:  " << root_a << ‘ ‘ << root_b << endl;
			int tmp = merge(root_a, root_b);
			fa[root_a] = fa[root_b] = tmp; //将两个节点父亲设为合并后的父亲
		}
		else {
			int a = read();
			int root_a = find(a);
			if (lt[a].val == 0) {printf ("-1\n"); continue;} //已被删除 输出-1
		//	cout << "find: " << root_a << endl;
			printf ("%d\n", lt[root_a].val);
			int tmp = merge (lt[root_a].lc, lt[root_a].rc);
			fa[lt[root_a].lc] = fa[lt[root_a].rc] =  tmp; //将左右子树的父亲设为它们合并后的父亲
			lt[root_a].lc = lt[root_a].rc = lt[root_a].val = 0; //删除堆顶
		}
	}
}