[BZOJ]1269文本编辑器 做题笔记

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <map>
using namespace std;
const int MAX=5000000;
int N,val;
char ch[20],s[5000000];
struct Splay {
int ch[MAX][2],s[MAX],f[MAX],cnt,root,pos;
char a[MAX];
bool b[MAX];
void filp (int x) {
if (!x) return ;
swap(ch[x][0],ch[x][1]);
b[x]^=1;
}
void push (int x) {
if (!x) return ;
if (b[x]) {
filp(ch[x][0]);filp(ch[x][1]);
b[x]=0;
}
}
void update (int x) {
s[x]=s[ch[x][0]]+s[ch[x][1]]+1;
}
void rotate (int x) {
int y=f[x],opt;
if (ch[f[x]][0]==x) opt=0;
else opt=1;
ch[y][opt]=ch[x][!opt];
if (ch[x][!opt]) f[ch[x][!opt]]=y;
f[x]=f[y];
if (root==y) root=x;
else if (ch[f[y]][0]==y) ch[f[y]][0]=x;
else ch[f[y]][1]=x;
f[y]=x,ch[x][!opt]=y;
update(y),update(x);
}
void splay (int x,int to=0) {
while (f[x]!=to) {
if (f[f[x]]==to) rotate(x);
else if ((ch[f[f[x]]][0]==f[x])
==(ch[f[x]][0]==x))
rotate(f[x]),rotate(x);
else rotate(x),rotate(x);
}
}
int build (int L,int R,int fa,char *s) {
if (L>R) return 0;
int x=++cnt,mid=(L+R)>>1;
f[x]=fa;
ch[x][0]=build(L,mid-1,x,s);
a[x]=s[val++];
ch[x][1]=build(mid+1,R,x,s);
update(x);
return x;
}
int find (int k) {
int x=root;push(x);
while (s[ch[x][0]]+1!=k) {
if (k<s[ch[x][0]]+1) x=ch[x][0];
else k-=s[ch[x][0]]+1,x=ch[x][1];
push(x);
}
return x;
}
void init () {
root=1,cnt=2,pos=1;
ch[1][1]=2,f[2]=1,s[1]=2,s[2]=1;
}
void insert (int len,char *s) {
splay(find(pos));splay(find(pos+1),root);
val=0;
ch[ch[root][1]][0]=build(0,len-1,ch[root][1],s);
update(ch[root][1]);
update(root);
}
void del (int n) {
splay(find(pos));splay(find(pos+n+1),root);
ch[ch[root][1]][0]=0;
update(ch[root][1]);
update(root);
}
void op (int n) {
splay(find(pos)),splay(find(pos+n+1),root);
filp(ch[ch[root][1]][0]);
}
Splay () { cnt=root=0; }
}Sp;
int main () {
int opt;
Sp.init();
scanf("%d",&N);
for (int i=1;i<=N;i++) {
scanf("%s",ch);
if (strcmp(ch,"Move")==0) {
scanf("%d",&opt);
Sp.pos=opt+1;
}
else if (strcmp(ch,"Insert")==0) {
scanf("%d%*c",&opt);
for (int j=0;j<opt;j++) {
s[j]=getchar();
}
Sp.insert(opt,s);
}
else if (strcmp(ch,"Delete")==0) {
scanf("%d",&opt);
Sp.del(opt);
}
else if (strcmp(ch,"Rotate")==0) {
scanf("%d",&opt);
Sp.op(opt);
}
else if (strcmp(ch,"Get")==0) {
printf("%c\n",Sp.a[Sp.find(Sp.pos+1)]);
}
else if (strcmp(ch,"Prev")==0) {
Sp.pos--;
}
else if (strcmp(ch,"Next")==0) {
Sp.pos++;
}
}
}