HDU2665-主席树&模板-Kth number

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https://vjudge.net/problem/HDU-2665
区间第k大，主席树模板题。
讲解主席树
http://blog.csdn.net/regina8023/article/details/41910615

#include <iostream>#include <algorithm>#include <bits/stdc++.h>using namespace std;typedef long long LL;typedef unsigned long long ULL;const LL INF = 1E9+9;const int maxn = 100006;const int LOG = 20;struct node{    int l,r;    int sum;}Node[maxn*LOG];int root[maxn],node_cnt;int numbers[maxn],num_cnt;int a[maxn];void build(int l,int r,int &rt){    rt=++node_cnt;    Node[rt].l=Node[rt].r=Node[rt].sum=0;    if(l==r)        return ;    int m=(l+r)>>1;    build(l,m,Node[rt].l);    build(m+1,r,Node[rt].r);}void update(int v,int l,int r,int &rt,int pre){    rt=++node_cnt;    Node[rt]=Node[pre];    ++Node[rt].sum;    if(l==r)        return ;    int m=(l+r)>>1;    if(v<=m)        update(v,l,m,Node[rt].l,Node[pre].l);    else        update(v,m+1,r,Node[rt].r,Node[pre].r);}int query(int k,int l,int r,int r1,int r2){    if(l==r)        return r;    int lnum=Node[Node[r2].l].sum-Node[Node[r1].l].sum;    int m=(l+r)>>1;    if(k<=lnum)        return query(k,l,m,Node[r1].l,Node[r2].l);    else        return query(k-lnum,m+1,r,Node[r1].r,Node[r2].r);}int main(){//  ios::sync_with_stdio(false);    int n,m;    int ncase;      scanf("%d",&ncase);     while(ncase--){        scanf("%d%d",&n,&m);        for(int i=1;i<=n;i++)        {            scanf("%d",&a[i]);    //      cin>>a[i];            numbers[i]=a[i];        }        sort(numbers+1,numbers+n+1);        num_cnt=unique(numbers+1,numbers+n+1)-numbers-1;        node_cnt=0;        root[0]=0;        build(1,num_cnt,root[0]);        for(int i=1;i<=n;i++)        {            int pos = lower_bound(numbers+1,numbers+num_cnt+1,a[i])-numbers;            update(pos,1,num_cnt,root[i],root[i-1]);        }        while(m--)        {            int L,R,K;            cin>>L>>R>>K;            int q=query(K,1,num_cnt,root[L-1],root[R]);            printf("%d\n",numbers[q]);        //  cout<<numbers[q]<<'\n';        }     }    return 0;}

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