hdu 4006/AvlTree

原题链接：http://acm.hdu.edu.cn/showproblem.php?pid=4006

这道题以前用c语言写的Avltree水过了。。

现在接触了c++重写一遍。。。

由于没有删除操作故不带垃圾回收，具体如下：

 #include<cstdio>
 #include<cstdlib>
 #include<iostream>
 #define Max_N 1000100
 inline int max(int &a, int &b){
     return a > b ? a : b;
 }
 struct Node *null;
 struct Node{
     int v, s, Height;
     Node *ch[];
     inline void
         set(int H = , int _v = , int _s = , Node *p = NULL){
             v = _v, s = _s, Height = H;
             ch[] = ch[] = p;
         }
     inline void push_up(){
         s = ch[]->s + ch[]->s + ;
         int t1 = !ch[]->s ? - : ch[]->Height;
         int t2 = !ch[]->s ? - : ch[]->Height;
         Height = max(t1, t2) + ;
     }
 };
 struct AvlTree{
     Node *tail, *root;
     Node stack[Max_N];
     int top;
     void init(){
         tail = &stack[];
         null = tail++;
         null->set();
         root = null;
     }
     Node *newNode(int v){
         Node *p = tail++;
         p->set(, v, , null);
         return p;
     }
     inline void rotate(Node* &x, int d){
         Node *k = x->ch[!d];
         x->ch[!d] = k->ch[d];
         k->ch[d] = x;
         x->push_up();
         k->push_up();
         x = k;
     }
     inline void Maintain(Node* &x, int d){
         if (x->ch[d]->Height - x->ch[!d]->Height == ){
             if (x->ch[d]->ch[d]->Height - x->ch[d]->ch[!d]->Height == ){
                 rotate(x, !d);
             } else if (x->ch[d]->ch[d]->Height - x->ch[d]->ch[!d]->Height == -){
                 rotate(x->ch[d], d), rotate(x, !d);
             }
         }
     }
     inline void insert(Node* &x, int v){
         if (x == null){
             x = newNode(v);
             return;
         } else {
             int d = v > x->v;
             insert(x->ch[d], v);
             x->push_up();
             Maintain(x, d);
         }
     }
     inline int find_kth(Node *x, int k){
         int t = ;
         for (; x != null;){
             t = x->ch[]->s;
             if (k == t + ) break;
             else if (k <= t) x = x->ch[];
             else k -= t + , x = x->ch[];
         }
         return x->v;
     }
     inline void insert(int v){
         insert(root, v);
     }
     inline void find_kth(int k){
         printf("%d\n", find_kth(root, root->s - k + ));
     }
 }Avl;
 int main(){
 #ifdef LOCAL
     freopen("in.txt", "r", stdin);
     freopen("out.txt", "w+", stdout);
 #endif
     char ch;
     int i, n, k, d;
     while (~scanf("%d %d", &n, &k)){
         Avl.init();
         for (i = ; i < n; i++){
             getchar();
             scanf("%c", &ch);
             if ('I' == ch) scanf("%d", &d), Avl.insert(d);
             else Avl.find_kth(k);
         }
     }
     return ;
 }