代码说明
对于一些变量进行说明：
| 变量名 | 说明 |
|---|---|
rt |
树根 |
ff[u] |
点 \(u\) 的父节点，特别地， ff[rt]=0 |
ch[u][0|1] |
点 \(u\) 的 左/右儿子 |
siz[u] |
点 \(u\) 及其子树大小 |
val[u] |
点 \(u\) 对应的值 |
recy[u] |
点 \(u\) 对应的 val[u] 出现的次数 |
代码
#include<cstdio>
#include<vector>
using namespace std;
#define rep(i,__l,__r) for(signed i=__l,i##_end_=__r;i<=i##_end_;++i)
#define fep(i,__l,__r) for(signed i=__l,i##_end_=__r;i>=i##_end_;--i)
#define writc(a,b) fwrit(a),putchar(b)
#define mp(a,b) make_pair(a,b)
#define ft first
#define sd second
#define LL long long
#define ull unsigned long long
#define uint unsigned int
#define pii pair< int,int >
#define Endl putchar('\n')
// #define FILEOI
// #define int long long
// #define int unsigned
#ifdef FILEOI
# define MAXBUFFERSIZE 500000
inline char fgetc(){
static char buf[MAXBUFFERSIZE+5],*p1=buf,*p2=buf;
return p1==p2&&(p2=(p1=buf)+fread(buf,1,MAXBUFFERSIZE,stdin),p1==p2)?EOF:*p1++;
}
# undef MAXBUFFERSIZE
# define cg (c=fgetc())
#else
# define cg (c=getchar())
#endif
template<class T>inline void qread(T& x){
char c;bool f=0;
while(cg<'0'||'9'<c)f|=(c=='-');
for(x=(c^48);'0'<=cg&&c<='9';x=(x<<1)+(x<<3)+(c^48));
if(f)x=-x;
}
inline int qread(){
int x=0;char c;bool f=0;
while(cg<'0'||'9'<c)f|=(c=='-');
for(x=(c^48);'0'<=cg&&c<='9';x=(x<<1)+(x<<3)+(c^48));
return f?-x:x;
}
template<class T,class... Args>inline void qread(T& x,Args&... args){qread(x),qread(args...);}
template<class T>inline T Max(const T x,const T y){return x>y?x:y;}
template<class T>inline T Min(const T x,const T y){return x<y?x:y;}
template<class T>inline T fab(const T x){return x>0?x:-x;}
inline int gcd(const int a,const int b){return b?gcd(b,a%b):a;}
inline void getInv(int inv[],const int lim,const int MOD){
inv[0]=inv[1]=1;for(int i=2;i<=lim;++i)inv[i]=1ll*inv[MOD%i]*(MOD-MOD/i)%MOD;
}
template<class T>void fwrit(const T x){
if(x<0)return (void)(putchar('-'),fwrit(-x));
if(x>9)fwrit(x/10);putchar(x%10^48);
}
inline LL mulMod(const LL a,const LL b,const LL mod){//long long multiplie_mod
return ((a*b-(LL)((long double)a/mod*b+1e-8)*mod)%mod+mod)%mod;
}
const int MAXN=1e5;
const int INF=0x3f3f3f3f;
class Splay{
private:
int rt;
int ff[MAXN+5];
int ch[MAXN+5][2];
int siz[MAXN+5];
int recy[MAXN+5];
int val[MAXN+5];
vector<int>pool;
inline void release(const int x){
if(x)pool.push_back(x);
}
inline int generate(){
int ret=pool.back();
pool.pop_back();
return ret;
}
public:
Splay(){
rt=0;
rep(i,1,MAXN)pool.push_back(i);
}
inline void pushup(const int x){
siz[x]=siz[ch[x][0]]+siz[ch[x][1]]+recy[x];
}
inline void Rotate(const int x){
int y=ff[x],z=ff[y],k=(ch[y][1]==x);
ch[z][ch[z][1]==y]=x;
ff[x]=z;
ch[y][k]=ch[x][k^1];
ff[ch[x][k^1]]=y;
ch[x][k^1]=y;
ff[y]=x;
pushup(y),pushup(x);
//注意 上传 的先后顺序
}
/*
void Rotate(int x)//旋转
{
register int y=ff[x];
register int z=ff[y];
register int k=ch[y][1]==x;//x是y的左或右儿子
ch[z][ch[z][1]==y]=x;
ff[x]=z;
ch[y][k]=ch[x][k^1];
ff[ch[x][k^1]]=y;
ch[x][k^1]=y;
ff[y]=x;
pushup(y);pushup(x);
}
*/
inline void splay(const int x,const int goal=0){
int y,z;
while(ff[x]!=goal){
y=ff[x],z=ff[y];
if(z!=goal)
(ch[z][0]==y)^(ch[y][0]==x)?Rotate(x):Rotate(y);
Rotate(x);
}
if(goal==0)rt=x;
pushup(x);
}
inline void Insert(const int x){
int u=rt,fa=0;
while(u && val[u]!=x)fa=u,u=ch[u][val[u]<x];
if(u)++recy[u];
else{
u=generate();
if(fa)ch[fa][val[fa]<x]=u;
ff[u]=fa,val[u]=x;
ch[u][0]=ch[u][1]=0;
siz[u]=recy[u]=1;
}
splay(u);
}
inline void Find(const int x){
int u=rt;
if(!u)return;
while(x!=val[u] && ch[u][val[u]<x])u=ch[u][val[u]<x];
splay(u);
}
inline int Next(const int x,const int f){
Find(x);
int u=rt;
if((f && val[u]>x) || (!f && val[u]<x))return u;
for(u=ch[u][f];ch[u][f^1];u=ch[u][f^1]);
return u;
}
inline void Delete(const int x){
int pre=Next(x,0);
int suf=Next(x,1);
// printf("pre_val == %d, suf_val == %d\n",val[pre],val[suf]);
splay(pre);
splay(suf,pre);
int del=ch[suf][0];
if(recy[del]>1){
--recy[del];
splay(del);
}
else{
if(ch[suf][0])release(ch[suf][0]);
ch[suf][0]=0;
splay(suf);
//这里需要 splay 吗 ?
}
}
inline int Atrnk(int rnk){
int u=rt,y;
if(siz[u]<rnk)return -INF;
while(233){
y=ch[u][0];
if(rnk>siz[y]+recy[u]){
rnk-=siz[y]+recy[u];
u=ch[u][1];
}
else if(rnk<=siz[y])u=ch[u][0];
else return val[u];
}
}
inline int Getrnk(const int x){
Find(x);
return siz[ch[rt][0]]+1;
}
inline int Getpre(const int x){
int u=Next(x,0);
return val[u];
}
inline int Getsuf(const int x){
int u=Next(x,1);
return val[u];
}
void chk_tre(int u=-1){
if(u==-1)u=rt;
printf("Now u == %d, ff == %d, val == %d, siz == %d, lc == %d, rc == %d, recy == %d\n",u,ff[u],val[u],siz[u],ch[u][0],ch[u][1],recy[u]);
if(ch[u][0])chk_tre(ch[u][0]);
if(ch[u][1])chk_tre(ch[u][1]);
}
}Tre;
int n,opt,x;
signed main(){
#ifdef FILEOI
freopen("file.in","r",stdin);
freopen("file.out","w",stdout);
#endif
Tre.Insert(INF);
Tre.Insert(-INF);
// Tre.chk_tre();
// Endl;
qread(n);
while(n--){
qread(opt,x);
if(opt==1)Tre.Insert(x);
else if(opt==2)Tre.Delete(x);
else if(opt==3)writc(Tre.Getrnk(x)-1,'\n');
else if(opt==4)writc(Tre.Atrnk(x+1),'\n');
else if(opt==5)writc(Tre.Getpre(x),'\n');
else writc(Tre.Getsuf(x),'\n');
// Tre.chk_tre();
// Endl;
}
return 0;
}