题目来源：HDU 3726 Graph and Queries

题意：见白书

思路：刚学treap 参考白皮书

#include <cstdio>
#include <cstring>
#include <cstdlib>
using namespace std;

struct Node
{
	Node *ch[2];
	int r;
	int v;
	int s;
	Node(int v): v(v) {
		ch[0] = ch[1] = NULL; r = rand(); s = 1;
	}
	bool operator < (const Node& rhs) const{
		return r < rhs.r;
	}
	int cmp(int x) const{
		if(x == v) return -1;
		return x < v ? 0 : 1;
	}
	void maintain(){
		s = 1;
		if(ch[0] != NULL) s += ch[0]->s;
		if(ch[1] != NULL) s += ch[1]->s;
	}
};

void rotate(Node* &o, int d){
	Node* k = o->ch[d^1]; o->ch[d^1] = k->ch[d]; k->ch[d] = o;
	o->maintain(); k->maintain(); o = k;
}

void insert(Node* &o, int x){
	if(o == NULL){
		o = new Node(x);
	}
	else{
		int d = (x < o->v ? 0 : 1);
		insert(o->ch[d], x);
		if(o->ch[d] > o) rotate(o, d^1);
	}
	o->maintain();
	//printf("--------+%d\n", o->s);
}

void remove(Node* &o, int x){
	int d = o->cmp(x);
	if(d == -1){
		Node* u = o;	
		if(o->ch[0] != NULL && o->ch[1] != NULL){			
			int d2 = o->ch[0] > o->ch[1] ? 1 : 0;
			rotate(o, d2); remove(o->ch[d2], x);
		}
		else{
			if(o->ch[0] == NULL) o = o->ch[1];
			else o = o->ch[0];
			delete u;
		}
	}
	else
		remove(o->ch[d], x);
	if(o != NULL) o->maintain();
}

HDU 3726 Graph and Queries treap树