1269: [AHOI2006]文本编辑器editor

#include<cstdio>
#include<iostream>
#include<ext/rope>
#include<algorithm>
using namespace std;
using namespace __gnu_cxx;
inline int read()
{
int x=0;char ch=getchar();
while(ch>'9'||ch<'0')ch=getchar();
while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
return x;
}
int n,now,len;
rope <char> a,b,tmp;
char s[2000000],rs[2000000];
int main()
{
n=read();
int x;
while(n--)
{
scanf("%s",s);
switch(s[0])
{
case 'M':now=read();break;
case 'P':now--;break;
case 'N':now++;break;
case 'G':printf("%c\n",a[now]);break;
case 'I':
{
x=read();len=a.length();
for(int i=0;i<x;i++)
{
s[i]=getchar();
while(s[i]=='\n') s[i]=getchar();
rs[x-i-1]=s[i];
}
rs[x]=s[x]=0;
a.insert(now,s);
b.insert(len-now,rs);
break;
}
case 'D':
{
x=read();len=a.length();
a.erase(now,x);
b.erase(len-now-x,x);
break;
}
case 'R':
{
x=read();len=a.length();
tmp=a.substr(now,x);
a=a.substr(0,now)+b.substr(len-now-x,x)+a.substr(now+x,len-now-x);
b=b.substr(0,len-now-x)+tmp+b.substr(len-now,now);
break;
}
}
}
return 0;
}