bzoj 1269 [AHOI2006]文本编辑器editor

原题链接：http://www.lydsy.com/JudgeOnline/problem.php?id=1269

伸展树的运用，如下：

 #include<cstdio>
 #include<cstdlib>
 #include<cstring>
 #include<iostream>
 #include<algorithm>
 using std::swap;
 const int Max_N = ;
 struct Node{
     char chr;
     int s;
     bool rev;
     Node *pre, *ch[];
     inline void
     set(char _chr = ' ', int _s = , Node *p = NULL){
         chr = _chr, s = _s, rev = ;
         pre = ch[] = ch[] = p;
     }
     inline void push_up(){
         s = ch[]->s + ch[]->s + ;
     }
     inline void update(){
         rev ^= ;
         swap(ch[], ch[]);
     }
     inline void push_down(){
         if (rev != ){
             rev ^= ;
             ch[]->update();
             ch[]->update();
         }
     }
 };
 struct SplayTree{
     char buf[Max_N];
     Node *tail, *root, *null;
     Node stack[Max_N], *store[Max_N];
     int top, pos;
     void init(){
         top = , pos = ;
         tail = &stack[];
         null = tail++;
         null->set();
         root = newNode(' ');
         root->ch[] = newNode(' ');
         root->ch[]->pre = root;
         root->ch[]->push_up();
         root->push_up();
     }
     inline Node *newNode(char chr){
         Node *p = null;
         if (!top) p = tail++;
         else p = store[--top];
         p->set(chr, , null);
         return p;
     }
     inline void rotate(Node *x, int c){
         Node *y = x->pre;
         y->push_down(), x->push_down();
         y->ch[!c] = x->ch[c];
         x->pre = y->pre;
         if (x->ch[c] != null) x->ch[c]->pre = y;
         if (y->pre != null) y->pre->ch[y->pre->ch[] != y] = x;
         x->ch[c] = y;
         y->pre = x;
         y->push_up();
         if (y == root) root = x;
     }
     inline void splay(Node *x, Node *f){
         if (x == root) return;
         for (; x->pre != f; x->push_down()){
             if (x->pre->pre == f){
                 rotate(x, x->pre->ch[] == x);
             } else {
                 Node *y = x->pre, *z = y->pre;
                 if (z->ch[] == y){
                     if (y->ch[] == x)
                         rotate(y, ), rotate(x, );
                     else rotate(x, ), rotate(x, );
                 } else {
                     if (y->ch[] == x)
                         rotate(y, ), rotate(x, );
                     else rotate(x, ), rotate(x, );
                 }
             }
         }
         x->push_up();
     }
     inline Node *built(int l, int r){
         if (l > r) return null;
         int mid = (l + r) >> ;
         Node *p = newNode(buf[mid]);
         p->ch[] = built(l, mid - );
         if (p->ch[] != null) p->ch[]->pre = p;
         p->ch[] = built(mid + , r);
         if (p->ch[] != null) p->ch[]->pre = p;
         p->push_up();
         return p;
     }
     inline void recycle(Node *x){
         if (x != null){
             recycle(x->ch[]);
             store[top++] = x;
             recycle(x->ch[]);
         }
     }
     inline Node *select(Node *x, int k){
         for (int t = ; x != null;){
             x->push_down();
             t = x->ch[]->s;
             if (k == t + ) break;
             else if (k <= t) x = x->ch[];
             else k -= t + , x = x->ch[];
         }
         return x;
     }
     inline void get_range(int x, int y){
         splay(select(root, x + ), null);
         splay(select(root, y + ), root);
     }
     inline void Gets(char *s){
         char c;
         while (c = getchar(), c != '\n') *s++ = c;
         *s = '\0';
     }
     inline void insert(int n){
         char c;
         scanf("%c", &c);
         Gets(buf + );
         get_range(pos, pos);
         Node *ret = built(, n);
         root->ch[]->ch[] = ret;
         ret->pre = root->ch[];
         root->ch[]->push_up();
         root->push_up();
     }
     inline void del(int n){
         get_range(pos, pos + n);
         Node* &ret = root->ch[];
         ret->ch[]->pre = null;
 #ifdef LOCAL
         recycle(ret->ch[]);
 #endif
         ret->ch[] = null;
         ret->push_up();
         root->push_up();
     }
     inline void rotate(int n){
         get_range(pos, pos + n);
         root->ch[]->ch[]->update();
     }
     inline  void get(){
         splay(select(root, pos + ), null);
         printf("%c\n", root->chr);
     }
     inline void move(){
         scanf("%d", &pos);
     }
     inline void prev(){
         pos--;
     }
     inline void next(){
         pos++;
     }
 }spt;
 int main(){
 #ifdef LOCAL
     freopen("in.txt", "r", stdin);
     freopen("out.txt", "w+", stdout);
 #endif
     spt.init();
     int m, n;
     char str[];
     scanf("%d", &m);
     while (m--){
         scanf("%s", str);
         switch (str[]){
             case 'M':
                 spt.move();
                 break;
             case 'I':
                 scanf("%d", &n);
                 spt.insert(n);
                 break;
             case 'D':
                 scanf("%d", &n);
                 spt.del(n);
                 break;
             case 'N':
                 spt.next();
                 break;
             case 'P':
                 spt.prev();
                 break;
             case 'R':
                 scanf("%d", &n);
                 spt.rotate(n);
                 break;
             case 'G':
                 spt.get();
                 break;
         }
     }
     return ;
 }