luoguP4008 [NOI2003]文本编辑器

题意

splay维护即可

code:

#include<bits/stdc++.h>
using namespace std;
const int maxn=2000010;
int T,tot,points,root;
int fa[maxn],size[maxn];
int ch[maxn][2];
char str[maxn],s[maxn];
queue<int>pool;
inline int read()
{
    char c=getchar();int res=0,f=1;
    while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
    while(c>='0'&&c<='9')res=res*10+c-'0',c=getchar();
    return res*f;
}
inline void up(int x){size[x]=size[ch[x][0]]+size[ch[x][1]]+1;}
inline bool get(int x){return ch[fa[x]][1]==x;}
inline void rotate(int x)
{
    int y=fa[x],z=fa[y],k=get(x),w=ch[x][k^1];
    if(z)ch[z][get(y)]=x;ch[x][k^1]=y;ch[y][k]=w;
    if(w)fa[w]=y;fa[y]=x;fa[x]=z;
    up(y),up(x);
}
inline void splay(int x,int goal=0)
{
    while(fa[x]!=goal)
    {
        int y=fa[x];
        if(fa[y]!=goal)rotate(get(x)==get(y)?y:x);
        rotate(x);
    }
    if(!goal)root=x;
}
inline int find(int x)
{
    int now=root;
    while(23333)
    {
        if(ch[now][0]&&x<=size[ch[now][0]])now=ch[now][0];
        else if(x>size[ch[now][0]]+1)x-=size[ch[now][0]]+1,now=ch[now][1];
        else return now;
    }
}
inline int build(int l,int r,char* s)
{
    if(l>r)return 0;
    int now,mid=(l+r)>>1;
    if(!pool.empty())now=pool.front(),pool.pop();
    else now=++tot;
    str[now]=s[mid];size[now]=1;
    ch[now][0]=build(l,mid-1,s),ch[now][1]=build(mid+1,r,s);
    if(ch[now][0])fa[ch[now][0]]=now;if(ch[now][1])fa[ch[now][1]]=now;
    up(now);
    return now;
}
inline void print(int x)
{
    if(ch[x][0])print(ch[x][0]);
    putchar(str[x]);
    if(ch[x][1])print(ch[x][1]);
}
inline void recycle(int x)
{
    if(ch[x][0])recycle(ch[x][0]);
    if(ch[x][1])recycle(ch[x][1]);
    pool.push(x);
    fa[x]=ch[x][0]=ch[x][1]=0;
}
inline void insert()
{
    int len=read();s[0]=' ';
    for(int i=1;i<=len;i++)
    {
        s[i]=getchar();
        if(s[i]=='\n'||s[i]=='\r')i--;
    }
    int x=find(points+1),y=find(points+2);
    splay(x),splay(y,x);
    int now=build(1,len,s);
    ch[y][0]=now;fa[now]=y;
    up(y),up(x);
}
inline void del()
{
    int len=read();
    int x=find(points+1),y=find(points+len+2);
    splay(x),splay(y,x);
    int now=ch[y][0];
    recycle(now);ch[y][0]=0;
    up(y),up(x);
}
inline void Get()
{
    int len=read();
    int x=find(points+1),y=find(points+len+2);
    splay(x),splay(y,x);
    print(ch[y][0]);
    puts("");
}
inline void init()
{
    root=++tot;str[root]='\n',size[root]=1;
    int tmp=++tot;fa[tmp]=root;str[tmp]='\n',size[tmp]=1;ch[root][1]=tmp;
    up(root);
}
int main()
{
    //freopen("test.in","r",stdin);
    //freopen("test.out","w",stdout);
    T=read();
    init();
    while(T--)
    {
        char op[10];scanf("%s",op);
        if(op[0]=='M')points=read();
        if(op[0]=='I')insert();
        if(op[0]=='D')del();
        if(op[0]=='G')Get();
        if(op[0]=='P')points--;
        if(op[0]=='N')points++;
    }
    return 0;
}