RT
我调了好久
应该是 $update$ 的位置

或者 $splay$ 操作写错了

形成的树不满足二叉树的性质

求救

Code：

#include<queue>
#include<ctime>
#include<vector>
#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<algorithm>
using namespace std;
namespace FastIO
{
bool sign;
char c;
template<class T>
inline void read(T &x)
{
	x=0;
	sign=false;
	for(c=getchar();c<'0'||c>'9';c=getchar()) 
		if(c=='-') 
			sign=true;
	for(;c>='0'&&c<='9';c=getchar()) 
		x=(x<<1)+(x<<3)+(c&15);
	x=(sign) ? ~x+1 : x;
	return;
}
char bcc[36];
int top=0;
template<class T>
inline void print(T x)
{
	top=0;
	if(!x) {
		putchar('0');
		return;
	}
	if(x<0) putchar('-'),x=~x+1;
	for(;x>0;x=x/10) 
		bcc[++top]=x%10+48;
	for(;top>=1;top--) 
		putchar(bcc[top]);
	return;
}
}
using FastIO::read;
using FastIO::print;

const int INF=0x7fffffff-1;
const int N=2e6+5;

struct node
{
	int val;
	int father;
	int size,cnt;
	int child[2];
	#define v(x) sp[x].val
	#define fa(x) sp[x].father
	#define s(x) sp[x].size
	#define c(x) sp[x].cnt
	#define ch(x,y) sp[x].child[y]
};
node sp[N];
int root,cnt;
#define ident(x) (ch(fa(x),1)==x)
#define mix(fat,now,s) { ch((fat),(s))=(now); fa((now))=(fat);}
#define update(now) {s(now)=s(ch(now,0))+s(ch(now,1))+c(now);}
inline void rotate(const int &now)
{
	int k=ident(now),ff=fa(now);
	mix(ff,ch(now,k^1),k);
	mix(fa(ff),now,ident(ff));
	mix(now,ff,k^1);
	update(ch(now,k^1));
	update(now);
	return;
}
inline void splay(int now,int top) //代表把x转到top的儿子，top为0则转到根结点
{
	int x,y;
	while(fa(now)!=top) {
		x=fa(now); y=fa(x);
		if(y!=top) (ident(x)^ident(y)) ? rotate(now) : rotate(x);
		rotate(now);
	}
	if(!top) root=now,s(0)=0;
	return;
}
inline void find(const int &key)
{
	int now=root;
	while(now>0&&v(now)!=key&&ch(now,(key>v(now)))!=0) 
		now=ch(now,(key>v(now)));
	splay(now,0);
	return;
}
inline int newnode(const int &key,const int &fa)
{
	cnt++;
	v(cnt)=key;
	fa(cnt)=fa;
	s(cnt)=1;
	c(cnt)=1;
	ch(cnt,1)=ch(cnt,0)=0;
	return cnt;
}
inline void insert(int &now,const int &key,const int &fa)
{
	if(!now) {
		now=newnode(key,fa);
		splay(now,0);
		return;
	}
	if(key==v(now)) {
		c(now)++;
		splay(now,0);
		return;
	}
	else insert(ch(now,(key>v(now))),key,now);
	update(now);
	return;
}
inline void erase(const int &key)
{
	find(key);
	if(c(root)>1) { c(root)--; return; }
	if(ch(root,1)) {
		int now=ch(root,1);
		while(ch(now,0)>0) 
			now=ch(now,0);
		splay(now,root);
		mix(ch(root,1),ch(root,0),0);
		root=ch(root,0);
		fa(now)=0;
		update(root);
	} 
	else root=ch(root,0),fa(root)=0;
	return;
}
inline int getpre(const int &key)
{
	find(key);
	if(v(root)<key) 
		return v(root);
	int now=ch(root,0);
	if(now==0) return -INF;
	while(ch(now,1))
		now=ch(now,1);
	splay(now,0);
	return v(now);
}
inline int getsuf(const int &key)
{
	find(key);
	if(v(root)>key) 
		return v(root);
	int now=ch(root,1);
	if(now==0) return INF;
	while(ch(now,0)) 
		now=ch(now,0);
	splay(now,0);
	return v(now);
}
inline int getrank(const int &key)
{
	getpre(key);
	return (v(root)==key) ? s(ch(root,0))+1 : s(ch(root,0))+c(root)+1;
}
inline int getnum(int rank)
{
	int now=root;
	while(now>0&&rank>0) {
		if(s(ch(now,0))>rank&&s(ch(now,0))+c(now)<=rank) {
			splay(now,0);
			break;
		}
		if(s(ch(now,0))+c(now)>rank) 
			now=ch(now,0);
		else rank-=s(ch(now,0))+c(now),now=ch(now,1);
	}
	return v(root);
}
int n;
int main()
{
//	freopen("bst.in","r",stdin);
//	freopen("bst.out","w",stdout);
	read(n);
	int opt,x;
	for(int i=1;i<=n;i++) {
		read(opt); read(x);
		switch(opt) {
			case 1 : insert(root,x,0); break;
			case 2 : erase(x); break;
			case 3 : print(getrank(x)); break;
			case 4 : print(getnum(x)); break;
			case 5 : print(getpre(x)); break;
			case 6 : print(getsuf(x)); break;
		}
		if(opt>=3&&opt<=6) 
			puts("");
	}
	return 0;
}

有一组数据

10
1 1
1 13
1 2
6 2
4 2
3 2
1 15
1 12
6 12
2 15

正确输出

13
2
2
13

我的输出

13
13
2
13

大佬救救我吧！