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=100055,inf=1000000000;
int read(){
    int ans=0,f=1,c=getchar();
    while(c<'0'||c>'9'){if(c=='-') f=-1; c=getchar();}
    while(c>='0'&&c<='9'){ans=ans*10+(c-'0'); c=getchar();}
    return ans*f;
}
int n,m,root;
int c[M][2],size[M],fa[M],v[M],pos[M];
void up(int k){size[k]=size[c[k][0]]+size[c[k][1]]+1;}
void rotate(int x,int& k){
    int y=fa[x],z=fa[y],l=0,r=1;
    if(c[y][1]==x) l=1,r=0;
    if(y==k) k=x;
    else{if(c[z][0]==y) c[z][0]=x; else c[z][1]=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][0]==y^c[y][0]==x) rotate(y,k);
            else rotate(x,k);
        }
        rotate(x,k);
    }
}
int find(int x,int rank){
    int l=c[x][0],r=c[x][1];
    if(size[l]+1==rank) return x;
    else if(size[l]>=rank) return find(l,rank);
    else return find(r,rank-size[l]-1);
}
int build(int l,int r){
    if(l>r) return 0;
    int m=(l+r)>>1;
    c[m][0]=build(l,m-1);
    c[m][1]=build(m+1,r);
    for(int i=0;i<2;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-1); y=find(root,k+1);
    splay(x,root); splay(y,c[x][1]);
    z=c[y][0]; c[y][0]=0; size[z]=fa[z]=0;
    up(y); up(x);
}
void move(int k,int w){
    int x,y,z=pos[k],rank;
    splay(z,root); rank=size[c[z][0]]+1;
    del(rank);
    if(w==-inf) x=find(root,1),y=find(root,2);
    else if(w==inf) x=find(root,n),y=find(root,n+1);
    else x=find(root,rank+w-1),y=find(root,rank+w);
    splay(x,root); splay(y,c[x][1]);
    size[z]=1; fa[z]=y; c[y][0]=z;
    up(y); up(x);
}
int main()
{
    int k,T;
    n=read(); m=read();
    for(int i=2;i<=n+1;i++) v[i]=read(),pos[v[i]]=i;
    root=build(1,n+2);
    char ch[15];
    while(m--){
        scanf("%s",ch); k=read();
        if(ch[0]=='T') move(k,-inf);
        if(ch[0]=='B') move(k,inf);
        if(ch[0]=='I') T=read(),move(k,T);
        if(ch[0]=='A') splay(pos[k],root),printf("%d\n",size[c[pos[k]][0]]-1);
        if(ch[0]=='Q') T=find(root,k+1),printf("%d\n",v[T]);
    }
    return 0;
}