poj 3481 平衡树

裸的treap

#include<stdio.h>
#include<algorithm>
#include<stdlib.h>
#include<cstring>
#include<iostream>
#include<string>
#include<cmath>
#include<vector>
#include<queue>
#include<map>
#include<iterator>
#include<stack>

using namespace std;

#define ll   __int64
#define MAXN  500010
#define inf  2000000007

struct node
{
    struct node *ch[2];
    int sz,key,num,pri;
};
typedef node * tree;
node base[MAXN],nil;
tree root,null,top;

void Init()
{
    top=base;
    root=null=&nil;
    null->ch[0]=null->ch[1]=null;
    null->key=null->pri=null->num=2147483647;
    null->sz=0;
}
inline int random()
{
    static int seed=703;
    return seed=int(seed *48271ll %2147483647);
}
inline tree newnode(int num,int key)
{
    top->num=num;
    top->key=key;
    top->pri=random();
    top->sz=1;
    top->ch[0]=top->ch[1]=null;
    return top++;
}
void Rotate(tree &x,bool d)
{
    tree y = x->ch[!d];
    x->ch[!d]=y->ch[d];
    y->ch[d]=x;
    x->sz=x->ch[0]->sz+1+x->ch[1]->sz;
    y->sz=y->ch[0]->sz+1+y->ch[1]->sz;
    x=y;
}
void Insert(tree &t,int num,int key)
{
    if(t==null)
        t=newnode(num,key);
    else
    {
        bool d=key>t->key;
        Insert(t->ch[d],num,key);
        (t->sz)++;
        if(t->pri<t->ch[d]->pri)
            Rotate(t,!d);
    }
}
void Delete(tree &t,int key)
{
    if(t->key!=key)
    {
        Delete(t->ch[key>t->key],key);
        (t->sz)--;
    }
    else if(t->ch[0]==null)
        t=t->ch[1];
    else if(t->ch[1]==null)
        t=t->ch[0];
    else
    {

        bool d=t->ch[0]->pri<t->ch[1]->pri;
        Rotate(t,d);
        Delete(t->ch[d],key);
    }
}
tree select(int k) //第k个
{
    tree t=root;
    int tmp;
    for(;;)
    {
        tmp=t->ch[0]->sz+1;
        if(k==tmp)
            return t;
        else if(k>tmp)
        {
            k-=tmp;
            t=t->ch[1];
        }
        else
            t=t->ch[0];
    }
}
int cnt;
int main()
{
    Init();
    int ty;
    cnt=0;

    while(scanf("%d",&ty)!=EOF)
    {
        if(ty==0)
            break;
        if(ty==1)
        {
            int num,key;
            scanf("%d%d",&num,&key);
            Insert(root,num,key);
            cnt++;
        }
        else if(ty==2)
        {
            if(cnt>0)
            {
                tree a=select(cnt);
                int b=a->key;
                //printf("%d\n",b);
                Delete(root,b);
                printf("%d\n",a->num);
                cnt--;
            }
            else
                printf("0\n");
        }
        else
        {
            if(cnt>0)
            {
                tree a=select(1);
                int b=a->key;
                Delete(root,b);
                printf("%d\n",a->num);
                cnt--;
            }
            else
                printf("0\n");
        }
    }
    return 0;
}