BZOJ 1507 splay

写完维修数列 这不是水题嘛233333

//By SiriusRen
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int N=5000050;
int n,pos=1,ch[N][2],fa[N],size[N],root,xx,cnt;
char op[15],ins[N],v[N];
void push_up(int x){size[x]=size[ch[x][0]]+size[ch[x][1]]+1;}
void rotate(int p){
    int q=fa[p],y=fa[q],f=(ch[q][1]==p);
    ch[q][f]=ch[p][!f],fa[ch[q][f]]=q;
    ch[p][!f]=q,fa[q]=p,fa[p]=y;
    if(y)ch[y][ch[y][1]==q]=p;
    push_up(q);
}
void splay(int x,int tp){
    for(int y;y=fa[x];rotate(x)){
        if(y==tp)break;
        if(fa[y]!=tp){
            if((ch[y][0]==x)^(ch[fa[y]][0]==y))rotate(x);
            else rotate(y);
        }
    }push_up(x);
    if(!tp)root=x;
}
int find(int x,int sz){
    if(size[ch[x][0]]+1==sz)return x;
    else if(size[ch[x][0]]>=sz)return find(ch[x][0],sz);
    else return find(ch[x][1],sz-size[ch[x][0]]-1);
}
int build(int l,int r,int father){
    if(l>r)return 0;
    int pos=++cnt;
    if(l==r){
        size[pos]=1;
        fa[pos]=father;
        v[pos]=ins[l];
        return pos;
    }
    int mid=(l+r)>>1;
    ch[pos][0]=build(l,mid-1,pos);
    fa[pos]=father;v[pos]=ins[mid];
    ch[pos][1]=build(mid+1,r,pos);
    push_up(pos);
    return pos;
}
void check(int x){
    if(ch[x][0])check(ch[x][0]);
    printf("%c",v[x]);
    if(ch[x][1])check(ch[x][1]);
}
int main(){
    scanf("%d",&n);
    root=1,size[1]=2,ch[1][0]=2,size[2]=1,fa[2]=1,cnt=2;
    for(int i=1;i<=n;i++){
        scanf("%s",op);
        if(op[0]=='I'){
            int fx=find(root,pos),fy=find(root,pos+1);
            splay(fx,0),splay(fy,fx);
            scanf("%d",&xx);
            for(int j=1;j<=xx;j++)
                while(scanf("%c",&ins[j]),ins[j]<32);
            ch[fy][0]=build(1,xx,fy);
            push_up(fy),push_up(fx);
//          check(root);
        }
        else if(op[0]=='M')scanf("%d",&pos),pos++;
        else if(op[0]=='P')pos--;
        else if(op[0]=='N')pos++;
        else if(op[0]=='D'){
            scanf("%d",&xx);
            xx=min(size[root],xx+pos+1);
            int fx=find(root,pos),fy=find(root,xx);
            splay(fx,0),splay(fy,fx);
            ch[fy][0]=0,push_up(fy),push_up(fx);
        }
        else{
            scanf("%d",&xx);
            int fx=find(root,pos),fy=find(root,min(pos+xx+1,size[root]));
            splay(fx,0),splay(fy,fx);
            check(ch[fy][0]),puts("");
        }
    }
}