POJ 3481 SBT做法

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <cmath>
#include <utility>
#include <vector>
#include <queue>
#include <map>
#include <set>
#define max(x,y) ((x)>(y)?(x):(y))
#define min(x,y) ((x)>(y)?(y):(x))
#define INF 0x3f3f3f3f
#define MAXN 100005

using namespace std;

int cnt, rt;

struct SBT
{
    int key, size, son[2], num;
}T[MAXN];

inline void PushUp(int x)
{
    T[x].size=T[T[x].son[0]].size+T[T[x].son[1]].size+1;
}

inline int Newnode(int key, int num)
{
    ++cnt;
    T[cnt].num=num;
    T[cnt].key=key;
    T[cnt].size=1;
    T[cnt].son[0]=T[cnt].son[1]=0;
    return cnt;
}

void Rotate(int p, int &x)
{
    int y=T[x].son[!p];
    T[x].son[!p]=T[y].son[p];
    T[y].son[p]=x;
    PushUp(x);
    PushUp(y);
    x=y;
}

void Maintain(int &x, int p) //维护SBT的!p子树
{
    if(T[T[T[x].son[p]].son[p]].size > T[T[x].son[!p]].size)
        Rotate(!p, x);
    else if(T[T[T[x].son[p]].son[!p]].size > T[T[x].son[!p]].size)
        Rotate(p, T[x].son[p]), Rotate(!p, x);
    else return;
    Maintain(T[x].son[0], 0);
    Maintain(T[x].son[1], 1);
    Maintain(x, 0);
    Maintain(x, 1);
}

void Insert(int key, int &x, int num)
{
    if(!x) x=Newnode(key, num);
    else
    {
        T[x].size++;
        Insert(key, T[x].son[key > T[x].key], num);
        Maintain(x, key > T[x].key);
    }
}

bool Delete(int key, int &x) //删除值为key的节点 key可以不存在
{
    if(!x) return 0;
    if(T[x].key == key)
    {
        if(!T[x].son[0])
        {
            x=T[x].son[1];
            return 1;
        }
        if(!T[x].son[1])
        {
            x=T[x].son[0];
            return 1;
        }
        int y=T[x].son[0];
        while(T[y].son[1])
            y=T[y].son[1];
        T[x].key=T[y].key;
        T[x].size--;
        return Delete(T[x].key, T[x].son[0]);
    }
    else
        if(Delete(key, T[x].son[key > T[x].key]))
        {
            T[x].size--;
            return 1;
        }
}

int GetPth(int p, int &x)
{
    if(!x) return 0;
    if(p == T[T[x].son[0]].size+1)
        return x;
    if(p > T[T[x].son[0]].size+1)
        return GetPth(p-T[T[x].son[0]].size-1, T[x].son[1]);
    else
        return GetPth(p, T[x].son[0]);
}

int main ()
{
    int p, key, num, x;
    while(scanf("%d", &p) && p)
    {
        switch (p)
        {
            case 1:
                scanf("%d%d", &num, &key);
                Insert(key, rt, num);
                break;
            case 2:
                x=GetPth(T[rt].size, rt);
                if(x)
                {
                    printf("%d\n",T[x].num);
                    Delete(T[x].key, rt);
                }
                else
                    printf("0\n");
                break;
            case 3:
                x=GetPth(1, rt);
                if(x)
                {
                    printf("%d\n",T[x].num);
                    Delete(T[x].key, rt);
                }
                else
                    printf("0\n");
        }
    }
    return 0;
}