Splay模板

蒟蒻成功达成一次性AC模板，在此纪念。

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#include<cstdio>using namespace std;int fa[100005],ch[100005][2],k[100005],size[100005],cnt[100005],m,ind=0,root=0;void update(int p){    size[p]=size[ch[p][0]]+size[ch[p][1]]+cnt[p];}void rotate(int p){    int q=fa[p],y=fa[q],x=ch[q][1]==p;    ch[q][x]=ch[p][x^1];fa[ch[q][x]]=q;    ch[p][x^1]=q;fa[q]=p;fa[p]=y;    if(y)if(ch[y][0]==q)ch[y][0]=p;    else if(ch[y][1]==q)ch[y][1]=p;    update(q);update(p);}void splay(int x){    for(int y;y=fa[x];rotate(x))if(fa[y])rotate((x==ch[y][0])==(y==ch[fa[y]][0])?y:x);    root=x;}int search(int v){    int p=root;    for(;p&&k[p]-v;)p=ch[p][k[p]<v];    return p;}void insert(int v){    if(!root)root=++ind,k[root]=v,fa[root]=ch[root][0]=ch[root][1]=0,size[root]=cnt[root]=1;    else if(search(v))splay(search(v)),cnt[root]++,size[root]++;    else{int x=root,y;for(;y=ch[x][k[x]<v];x=y);y=++ind;k[y]=v;    size[y]=cnt[y]=1;fa[y]=x;ch[x][k[x]<v]=y;ch[y][0]=ch[y][1]=0;splay(y);}}void remove(int p){    if(!p)return;    splay(p);if(cnt[p]>1){size[p]--,cnt[p]--;return;}    int l=ch[p][0],r=ch[p][1],t;ch[p][0]=ch[p][1]=fa[l]=fa[r]=0;    for(t=l;ch[t][1];t=ch[t][1]);if(!t){root=r;return;}    splay(t);ch[root][1]=r;fa[r]=root;update(root);}int grank(int p){    if(!p)return 0;    splay(p);    return size[ch[p][0]]+1;}int kth(int _k){    int p=root,k=_k;    while(p){        if(ch[p][0])            if(k>size[ch[p][0]]&&k<=size[ch[p][0]]+cnt[p])return p;            else if(k<=size[ch[p][0]])p=ch[p][0];            else k-=size[ch[p][0]]+cnt[p],p=ch[p][1];        else            if(k<=cnt[p])return p;            else k-=cnt[p],p=ch[p][1];    }    return 0;}int prefix(int p){    if(!p)return 0;    splay(p);    int t=ch[p][0];    while(ch[t][1])t=ch[t][1];    return t;}int suffix(int p){    if(!p)return 0;    splay(p);    int t=ch[p][1];    while(ch[t][0])t=ch[t][0];    return t;}int main(){    int c,t;    scanf("%d",&m);    for(int i=0;i<m;i++){        scanf("%d%d",&c,&t);        switch(c){            case 1:insert(t);break;            case 2:remove(search(t));break;            case 3:printf("%d\n",grank(search(t)));break;            case 4:printf("%d\n",k[kth(t)]);break;            case 5:insert(t);printf("%d\n",k[prefix(search(t))]);remove(search(t));break;            case 6:insert(t);printf("%d\n",k[suffix(search(t))]);remove(search(t));break;        }    }}