treap by:刘汝佳

来源：互联网发布：郑州软件编辑：程序博客网时间：2024/06/13 03:12
备忘白书代码的基础上有细微改进
// Rank Tree// Rujia Liu// 输入格式：// m     操作有m个// 1 x   插入元素x// 2 x   删除元素x。如果成功，输入1，否则输出0// 3 k   输出第k小元素。k=1为最小元素// 4 x   输出值x的“名次”，即比x小的结点个数加1#include<cstdlib>struct Node {  Node *ch[2]; // 左右子树  int r; // 随机优先级  int v; // 值  int s; // 结点总数  Node(int v = 0):v(v) { ch[0] = ch[1] = NULL; r = rand(); s = 1; }  int cmp(int x) const {    if (x == v) return -1;    return x < v ? 0 : 1;  }  void maintain() {    s = 1;    if(ch[0] != NULL) s += ch[0]->s;    if(ch[1] != NULL) s += ch[1]->s;  }};void rotate(Node* &o, int d) {  Node* k = o->ch[d^1]; o->ch[d^1] = k->ch[d]; k->ch[d] = o;   o->maintain(); k->maintain(); o = k;}void insert(Node* &o, int x) {  if(o == NULL) o = new Node(x);  else {    int d = (x < o->v ? 0 : 1); // 不要用cmp函数，因为可能会有相同结点    insert(o->ch[d], x);    if(o->ch[d]->r > o->r) rotate(o, d^1);  }  o->maintain();}Node* find(Node* o, int x) {  if(o == NULL) return NULL;  if(x == o->v) return o;  return x < o->v ? find(o->ch[0], x) : find(o->ch[1], x);}// 要确保结点存在void remove(Node* &o, int x) {  int d = o->cmp(x);  int ret = 0;//没什么用的样子  if(d == -1) {    Node* u = o;    if(o->ch[0] != NULL && o->ch[1] != NULL) {      int d2 = (o->ch[0]->r > o->ch[1]->r ? 1 : 0);      rotate(o, d2); remove(o->ch[d2], x);    } else {      if(o->ch[0] == NULL) o = o->ch[1]; else o = o->ch[0];      delete u;//原版白书没有真实地将内存释放    }  } else    remove(o->ch[d], x);  if(o != NULL) o->maintain();}int kth(Node* o, int k) {  if(o == NULL || k <= 0 || k > o->s) return 0;  int s = (o->ch[0] == NULL ? 0 : o->ch[0]->s);  if(k == s+1) return o->v;  else if(k <= s) return kth(o->ch[0], k);  else return kth(o->ch[1], k-s-1);}// 在以o为根的子树中，值比x小的结点总数加1int rank(Node* o, int x) {  if(o == NULL) return 1;  if(x <= o->v) return rank(o->ch[0], x);  return rank(o->ch[1], x) + (o->ch[0] == NULL ? 0 : o->ch[0]->s) + 1;}#include<cstdio>const int INF = 0x7f7f7f7f;int main() {  int m, c, v;  Node* root = new Node(INF);  while(scanf("%d", &m) == 1) {    while(m--) {      scanf("%d%d", &c, &v);      if(c == 1) insert(root, v);      else if(c == 2) {        Node* o = find(root, v);        printf("%d\n", o == NULL ? 0 : 1);        if(o != NULL) remove(root, v);      }      else if(c == 3) printf("%d\n", kth(root, v));      else if(c == 4) printf("%d\n", rank(root, v));    }  }  return 0;}
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