P3369 【模板】普通平衡树 treap树旋转版

 

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#include<bits/stdc++.h> #define INF INT_MAX using namespace std; const int maxn=100010; int sum=0,R=0; int sz[maxn],v[maxn],num[maxn],rd[maxn],son[maxn][2]; //更新p子树的大小 void pushup(int p){      sz[p]=sz[son[p][0]]+sz[son[p][1]]+num[p]; } //旋转 void rot(int&p,int d){      int k=son[p][d^1];      son[p][d^1]=son[k][d];      son[k][d]=p;      pushup(p);      pushup(k);      p=k; } //插入 void ins(int &p,int x){      if (!p){         p=++sum;         sz[p]=num[p]=1;         v[p]=x;         rd[p]=rand();         return ;      }      if(v[p]==x){         num[p]++;         sz[p]++;         return ;      }      int d=(x>v[p]);//右子树      ins(son[p][d],x);      if (rd[p]<rd[son[p][d]]) rot(p,d^1);      pushup(p); } //删除 void del(int &p,int x){      if(!p) return ;      if(x<v[p]) del(son[p][0],x);      else if(x>v[p]) del(son[p][1],x);      else {           if(!son[p][0]&&!son[p][1]){               num[p]--;sz[p]--;               if (!num[p]) p=0;           }           else if(!son[p][1]){                rot(p,1);                del(son[p][1],x);           }           else if(!son[p][0]){                rot(p,0);                del(son[p][0],x);           }           else{                int d=(rd[son[p][0]]>rd[son[p][1]]);                rot(p,d);                del(son[p][d],x);           }      }      pushup(p); } //x的排名 int get_rank(int p,int x){     if(!p) return 0;     if(v[p]==x) return sz[son[p][0]]+1;     if(v[p]<x) return sz[son[p][0]]+num[p]+get_rank(son[p][1],x);     if(v[p]>x) return get_rank(son[p][0],x); } //排名x的值 int func_find(int p,int x){     if(!p) return 0;     if(sz[son[p][0]]>=x) return func_find(son[p][0],x);     else if(sz[son[p][0]]+num[p]<x)          return func_find(son[p][1],x-num[p]-sz[son[p][0]]);     else return v[p]; } //前驱 int pre(int p,int x){     if (!p) return -INF;     if (v[p]>=x) return pre(son[p][0],x);     else return max(v[p],pre(son[p][1],x)); } //后继 int suc(int p,int x){     if (!p) return INF;     if(v[p]<=x) return suc(son[p][1],x);     else return min(v[p],suc(son[p][0],x)); } int main() {     int n,op,x;     cin>>n;     while(n--)     {         cin>>op>>x;         if (op==1) ins(R,x);         else if(op==2) del(R,x);         else if(op==3) cout<<get_rank(R,x)<<endl;         else if(op==4) cout<<func_find(R,x)<<endl;         else if(op==5) cout<<pre(R,x)<<endl;         else if(op==6) cout<<suc(R,x)<<endl;     } }