bzoj1861 书架 splay版

单点插入删除以及求前缀

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int M=,inf=;
int read(){
    int ans=,f=,c=getchar();
    while(c<''||c>''){if(c=='-') f=-; c=getchar();}
    while(c>=''&&c<=''){ans=ans*+(c-''); c=getchar();}
    return ans*f;
}
int n,m,root;
int c[M][],size[M],fa[M],v[M],pos[M];
void up(int k){size[k]=size[c[k][]]+size[c[k][]]+;}
void rotate(int x,int& k){
    int y=fa[x],z=fa[y],l=,r=;
    if(c[y][]==x) l=,r=;
    if(y==k) k=x;
    else{if(c[z][]==y) c[z][]=x; else c[z][]=x;}
    fa[y]=x; fa[x]=z; fa[c[x][r]]=y;
    c[y][l]=c[x][r]; c[x][r]=y;
    up(y); up(x);
}
void splay(int x,int& k){
    while(x!=k){
        int y=fa[x],z=fa[y];
        if(y!=k){
            if(c[z][]==y^c[y][]==x) rotate(y,k);
            else rotate(x,k);
        }
        rotate(x,k);
    }
}
int find(int x,int rank){
    int l=c[x][],r=c[x][];
    if(size[l]+==rank) return x;
    else if(size[l]>=rank) return find(l,rank);
    else return find(r,rank-size[l]-);
}
int build(int l,int r){
    if(l>r) return ;
    int m=(l+r)>>;
    c[m][]=build(l,m-);
    c[m][]=build(m+,r);
    for(int i=;i<;i++) if(c[m][i]) fa[c[m][i]]=m;
    up(m); return m;
}
void del(int k){
    int x,y,z;
    x=find(root,k-); y=find(root,k+);
    splay(x,root); splay(y,c[x][]);
    z=c[y][]; c[y][]=; size[z]=fa[z]=;
    up(y); up(x);
}
void move(int k,int w){
    int x,y,z=pos[k],rank;
    splay(z,root); rank=size[c[z][]]+;
    del(rank);
    if(w==-inf) x=find(root,),y=find(root,);
    else if(w==inf) x=find(root,n),y=find(root,n+);
    else x=find(root,rank+w-),y=find(root,rank+w);
    splay(x,root); splay(y,c[x][]);
    size[z]=; fa[z]=y; c[y][]=z;
    up(y); up(x);
}
int main()
{
    int k,T;
    n=read(); m=read();
    for(int i=;i<=n+;i++) v[i]=read(),pos[v[i]]=i;
    root=build(,n+);
    char ch[];
    while(m--){
        scanf("%s",ch); k=read();
        if(ch[]=='T') move(k,-inf);
        if(ch[]=='B') move(k,inf);
        if(ch[]=='I') T=read(),move(k,T);
        if(ch[]=='A') splay(pos[k],root),printf("%d\n",size[c[pos[k]][]]-);
        if(ch[]=='Q') T=find(root,k+),printf("%d\n",v[T]);
    }
    return ;
}