HYSBZ 1269 文本编辑器editor(Splay)

           对一个字符串进行各种操作……写完感觉需要写的没想象中的多，对于光标的位置，用一个变量来记录，表示光标在第k个字符之后，这样Move，Prev和Next就直接改变这个变量，为了操作方便，在最开始和最后各插入一个字符。剩下的操作就不难写了，翻转操作用个懒惰标记就能搞定，insert把第k个旋转到根，把第k+1旋转到根下面，然后插入，Delete也类似，Get只要获取第k个字符的值就好了。

代码：

#include<iostream>#include<cstdio>#include<cstring>#include<string>#include<algorithm>#include<map>#include<queue>#include<set>#include<stack>#include<cmath>#include<vector>#define inf 0x3f3f3f3f#define Inf 0x3FFFFFFFFFFFFFFFLL#define eps 1e-9#define pi acos(-1.0)using namespace std;typedef long long ll;const int maxn=1024*1024*2+10;int ch[maxn][2],pre[maxn],val[maxn],size[maxn],flip[maxn];char str[maxn],s[20];int root,tot;void NewNode(int &rt,int fa,int v){    rt=++tot;    ch[rt][0]=ch[rt][1]=0;    pre[rt]=fa;val[rt]=v;    size[rt]=1;flip[rt]=0;}inline void PushUp(int rt){    size[rt]=size[ch[rt][0]]+size[ch[rt][1]]+1;}inline void PushDown(int rt){    if(flip[rt])    {        flip[ch[rt][0]]^=1;        flip[ch[rt][1]]^=1;        swap(ch[rt][0],ch[rt][1]);        flip[rt]=0;    }}void Rotate(int x,int kind){    int y=pre[x];    PushDown(x);PushDown(y);    ch[y][kind^1]=ch[x][kind];    pre[ch[x][kind]]=y;    if(pre[y]) ch[pre[y]][ch[pre[y]][1]==y]=x;    pre[x]=pre[y];    ch[x][kind]=y;    pre[y]=x;    PushUp(y);}void Splay(int rt,int goal){    PushDown(rt);    while(pre[rt]!=goal)    {        int y=pre[rt];        if(pre[y]==goal)            Rotate(rt,ch[y][0]==rt);        else        {            int kind=ch[pre[y]][0]==y;            if(ch[y][kind]==rt)            {                Rotate(rt,kind^1);                Rotate(rt,kind);            }            else            {                Rotate(y,kind);                Rotate(rt,kind);            }        }    }    PushUp(rt);    if(goal==0) root=rt;}void RotateTo(int k,int goal){    int rt=root;    PushDown(rt);    while(size[ch[rt][0]]!=k)    {        if(size[ch[rt][0]]>k)            rt=ch[rt][0];        else        {            k-=(size[ch[rt][0]]+1);            rt=ch[rt][1];        }        PushDown(rt);    }    Splay(rt,goal);}void Insert(int k,int rc){    RotateTo(k,0);    RotateTo(k+1,root);    int rt=ch[root][1];    pre[rc]=rt;    ch[rt][0]=rc;    PushUp(rt);    PushUp(root);}void build(int l,int r,int &rt,int fa){    if(l>r) return ;    int m=(l+r)>>1;    NewNode(rt,fa,(int)str[m]);    build(l,m-1,ch[rt][0],rt);    build(m+1,r,ch[rt][1],rt);    PushUp(rt);}void Del(int k,int len){    RotateTo(k,0);    RotateTo(k+len+1,root);    int rt=ch[root][1];    ch[rt][0]=0;    PushUp(rt);    PushUp(root);}void Filp(int k,int len){    RotateTo(k,0);    RotateTo(k+len+1,root);    flip[ch[ch[root][1]][0]]^=1;}char Get(int k){    RotateTo(k+1,0);    return val[root];}void Init(){    ch[0][0]=ch[0][1]=size[0]=val[0]=0;    pre[0]=flip[0]=root=tot=0;    NewNode(root,0,0);    NewNode(ch[root][1],root,0);    PushUp(root);}int main(){    //freopen("in.txt","r",stdin);    //freopen("out.txt","w",stdout);    int n;    while(~scanf("%d",&n))    {        Init();        int x,rc,pos=0;        while(n--)        {            scanf("%s",s);            if(s[0]=='M')                scanf("%d",&pos);            else if(s[0]=='I')            {                scanf("%d",&x);                getchar();                gets(str);                build(0,x-1,rc,0);                Insert(pos,rc);            }            else if(s[0]=='D')            {                scanf("%d",&x);                Del(pos,x);            }            else if(s[0]=='R')            {                scanf("%d",&x);                Filp(pos,x);            }            else if(s[0]=='G')                printf("%c\n",Get(pos));            else if(s[0]=='P')                pos--;            else pos++;        }    }    return 0;}