白书上的Treap模板

改良

#include <iostream>
#include <ctime>
#include <cstdlib>
#define MAX 100
using namespace std;

const int MAX_NODE=100;
struct Node{
    Node* ch[2];//左右子树
    int fix;//优先级。数值越大，优先级越高
    int key;
    int size;//以它为根的子树的总结点数
    bool operator<(const Node& rhs) const {
        return key<rhs.key;
    }
    int cmp(int x) const{
        if (x==key) return -1;
        return x<key?0:1;
    }
    //名次树
    void maintain(){
        size=1;
        if (ch[0]!=NULL) size+=ch[0]->size;
        if (ch[1]!=NULL) size+=ch[1]->size;
    }
};

struct Treap{
    Node nodePool[MAX_NODE],*cur;
    Node* root;
    Treap(){
        srand(time(0));
        cur=nodePool;
        root=NULL;
    }
    void clear(){
        srand(time(0));
        cur=nodePool;
        root=NULL;
    }
    Node* newNode(){
        Node* t=cur++;
        return t;
    }
    //d=0代表左旋,d=1代表右旋
    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;
    }
    //在以o为根的子树中插入键值x,修改o
    void insert(Node* &o,int x){
        if (o==NULL){
            o=newNode();
            o->ch[0]=o->ch[1]=NULL;
            o->key=x;
            o->fix=rand();
        }
        else
        {
            int d=o->cmp(x);
            if (d!=-1){
                insert(o->ch[d],x);
                if (o->ch[d]>o) rotate(o,d^1);
            }
        }
    }
    void remove(Node* &o,int x){
        int d=o->cmp(x);
        if (d==-1){
            if (o->ch[0]==NULL) o=o->ch[1];
            else if (o->ch[1]==NULL) o=o->ch[0];
            else{
                int d2=(o->ch[0]>o->ch[1]?1:0);
                rotate(o,d2);
                remove(o->ch[d2],x);
            }
        }
        else remove(o->ch[d],x);
    }
    bool find(Node* o,int x){
        while (o!=NULL){
            int d=o->cmp(x);
            if (d==-1) return 1;
            else o=o->ch[d];
        }
        return 0;
    }
};