poj 1442 名次树

  1 //insert 插入
  2 //remove 删除
  3 //_find 查找
  4 //kth 返回root为根的树中第k小的元素
  5 //treap插入、删除、查询时间复杂度均为O(logn)
  6 #include <iostream>
  7 #include <cstring>
  8 #include <cstdlib>
  9 #include <ctime>
 10 #include <cstdio>
 11 using namespace std;
 12 int a[300010],n,m;
 13 struct Node
 14     {
 15         Node *ch[2];
 16         int r,v,s;
 17         Node(int v):v(v)
 18             {s=1;ch[0]=ch[1]=NULL;r=rand();}
 19         int cmp(int x) const{
 20             if(x==v)return(-1);
 21             return (x<v)?(0):(1);
 22         }
 23         void maintain(){
 24             s=1;
 25             if(ch[0]!=NULL)s+=ch[0]->s;
 26             if(ch[1]!=NULL)s+=ch[1]->s;
 27         }
 28     };
 29 void rotate(Node* &o,int d)
 30     {
 31         Node* k=o->ch[d^1];
 32         o->ch[d^1]=k->ch[d];
 33         k->ch[d]=o;
 34         o->maintain();
 35         k->maintain();
 36         o=k;
 37     }
 38 void insert(Node* &o,int x)
 39     {
 40         if(o==NULL) o=new Node(x);
 41         else {
 42             int d=(x<o->v)?0:1;
 43             insert(o->ch[d],x);
 44             if((o->r)<(o->ch[d]->r))
 45                 rotate(o,d^1);
 46         }
 47         o->maintain();
 48     }
 49 void remove(Node* &o,int x)
 50     {
 51         int d=o->cmp(x);
 52         if(d==-1){
 53             Node* u=o;
 54             if(o->ch[0]==NULL){o=o->ch[1];delete u;}else
 55             if(o->ch[1]==NULL){o=o->ch[0];delete u;}else {
 56                 int c=(o->ch[0])>(o->ch[1])?(1):(0);
 57                 rotate(o,c);
 58                 remove(o->ch[c],x);
 59             }
 60         }
 61         else remove(o->ch[d],x);
 62         if(o!=NULL) o->maintain();
 63     }
 64 int find(Node* &o,int x)
 65     {
 66         while(o!=NULL){
 67             int d=o->cmp(x);
 68             if(d==-1)
 69                 return 1;
 70             else
 71                 o=o->ch[d];
 72         }
 73         return 0;
 74     }
 75 int kth(Node* o,int k)
 76     {
 77         while(o!=NULL){
 78             int lchsize=(o->ch[0]!=NULL)?
 79                         (o->ch[0]->s):0;
 80             if(lchsize+1==k)
 81                 return o->v;
 82             else {
 83                 int d=(lchsize<k);
 84                 o=o->ch[d];
 85                 k-=d*(lchsize+1);
 86             }
 87         }
 88         return 0;
 89     }
 90 
 91 int main()
 92 {
 93     Node* root=NULL;
 94     int u,ans,p=0;
 95     srand(time(0));
 96 
 97     cin>>m>>n;
 98     for(int i=0;i<m;i++)
 99         cin>>a[i];
100     for(int i=1;i<=n;i++)
101     {
102         cin>>u;
103         while(p<u)
104             insert(root,a[p++]);
105         ans=kth(root,i);
106         cout<<ans<<endl;
107     }
108     return 0;
109 }