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;
}