[AHOI2006]文本编辑器editor (Splay tree)

转载请注明出处，谢谢 http://blog.csdn.net/ACM_cxlove?viewmode=contents           by---cxlove

通过一个变量记录光标的位置即可。

MOVE：直接改变光标位置变量

INSERT：经典旋转，插入到根的右孩子的左子树

ROTATE：经典操作，区间反转，通过一个延迟标记记录，交换左右子树。同样要用到经典的旋转

GET：得到光标位置的后继，可以GET_KTH后然后GET_NEXT，也可以直接旋转，或者旋转后GET_MIN

PREV,NEXT：都只需要改变光标位置变量

在指定旋转的时候，我用的是GET_KTH，找到位置然后再Splay旋转，也有直接旋转的，代码里也加了

#include<iostream>#include<cstring>#include<queue>#include<cstdio>#include<algorithm>#define N 1024*1024*2#define inf 1<<29#define MOD 100000007#define LL long long#define Key_value ch[ch[root][1]][0]#define _match(a,b) ((a)==(b))using namespace std;int n,q;char key[N];int size[N],pre[N],rev[N],pos;int ch[N][2],tot,root,node[N];//debug部分copy from hh  void Treaval(int x) {      if(x) {          Treaval(ch[x][0]);          printf("结点%2d:左儿子 %2d 右儿子 %2d 父结点 %2d size = %2d ,key = %2c \n",x,ch[x][0],ch[x][1],pre[x],size[x],key[x]);          Treaval(ch[x][1]);      }  }  void debug() {printf("%d\n",root);Treaval(root);}  //以上Debug  void NewNode(int &r,char k,int father){r=++tot;ch[r][0]=ch[r][1]=0;pre[r]=father;rev[r]=0;key[r]=k;}void Push_Up(int r){size[r]=size[ch[r][0]]+size[ch[r][1]]+1;}void Push_Down(int r){if(rev[r]){swap(ch[r][0],ch[r][1]);rev[ch[r][0]]^=1;rev[ch[r][1]]^=1;rev[r]=0;}}void Bulid(int &r,int L,int R,int father,char *str){if(L>R)return ;int mid=(L+R)/2;NewNode(r,str[mid],father);Bulid(ch[r][0],L,mid-1,r,str);Bulid(ch[r][1],mid+1,R,r,str);Push_Up(r);}void Init(){tot=root=0;ch[root][0]=ch[root][1]=pre[root]=rev[root]=size[root]=0;Bulid(root,0,4,0,"     ");}void Rotate(int x,int kind){  int y=pre[x];    Push_Down(y);Push_Down(x);ch[y][!kind]=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;  Push_Up(y);  }   void Splay(int r,int goal){  Push_Down(r);while(pre[r]!=goal){  if(pre[pre[r]]==goal)  Rotate(r,ch[pre[r]][0]==r);  else{  int y=pre[r];  int kind=(ch[pre[y]][0]==y);  if(ch[y][kind]==r){  Rotate(r,!kind);  Rotate(r,kind);  }  else{  Rotate(y,kind);  Rotate(r,kind);  }  }  }  Push_Up(r);  if(goal==0) root=r;  } void RotateTo(int k,int goal) {      int r=root;      Push_Down(r);      while(size[ch[r][0]]!=k){          if(k<size[ch[r][0]]){              r=ch[r][0];          } else {              k-=(size[ch[r][0]]+1);              r=ch[r][1];          }          Push_Down(r);      }      Splay(r,goal);  }  int Get_Kth(int r,int k){Push_Down(r);int t=size[ch[r][0]]+1;if(t==k)return r;if(t>k)return Get_Kth(ch[r][0],k);elsereturn Get_Kth(ch[r][1],k-t);}int Get_Min(int r){Push_Down(r);while(ch[r][0]){r=ch[r][0];Push_Down(r);}return r;}int Get_Max(int r){Push_Down(r);while(ch[r][1]){r=ch[r][1];Push_Down(r);}return r;}void Reversal(int k){int x=Get_Kth(root,pos);Splay(x,0);int y=Get_Kth(root,pos+k+1);Splay(y,root);rev[Key_value]^=1;}void Cut(int a,int b,int c){int x=Get_Kth(root,a);int y=Get_Kth(root,b+2);Splay(x,0);Splay(y,root);int tmp=Key_value;Key_value=0;Push_Up(ch[root][1]);Push_Up(root);int z=Get_Kth(root,c+1);Splay(z,0);int m=Get_Min(ch[root][1]);Splay(m,root);Key_value=tmp;pre[Key_value]=ch[root][1];Push_Up(ch[root][1]);Push_Up(root);}int cnt;void InOrder(int r){if(r==0)return;Push_Down(r);InOrder(ch[r][0]);if(cnt>=1&&cnt<=size[root]-5)    printf("%c",key[r]);cnt++;InOrder(ch[r][1]);}void Insert(char *str){int len=strlen(str); int x=Get_Kth(root,pos);Splay(x,0);//RotateTo(pos,0);int m=Get_Min(ch[root][1]);Splay(m,root);Bulid(Key_value,0,len-1,ch[root][1],str);}void Delete(int k){//RotateTo(pos,0);int x=Get_Kth(root,pos);Splay(x,0);int y=Get_Kth(root,pos+k+1);Splay(y,root);pre[Key_value]=0;Key_value=0;Push_Up(ch[root][1]);Push_Up(root);}char Get_Answer(){int x=Get_Kth(root,pos);Splay(x,0);//RotateTo(pos,0);int y=Get_Min(ch[root][1]);return key[y];}char str[N];int main(){//freopen("editor1.in","r",stdin);while(scanf("%d",&q)!=EOF){Init();int k;pos=1;//光标初始位置while(q--){scanf("%s",str,&k);if(str[0]=='I'){scanf("%d",&k);getchar();gets(str);Insert(str);}else if(str[0]=='M'){scanf("%d",&k);pos=k+1;}else if(str[0]=='D'){scanf("%d",&k);Delete(k);}else if(str[0]=='R'){scanf("%d",&k);Reversal(k);}else if(str[0]=='G')printf("%c\n",Get_Answer());else if(str[0]=='P')pos--;elsepos++;}}return 0;}