主席树模板

 1 /**
 2 * Copyright(c)
 3 * All rights reserved.
 4 * Author : @klay
 5 * Date : 2018-08-27-16.18.54
 6 * Description 主席树模板动态第k小
 7 */
 8 #include<iostream>
 9 #include<cstdio>
10 #include<algorithm>
11 #include<vector>
12 #include<cstring>
13 #include<map>
14 #include<set>
15 #include<queue>
16 #include<bitset>
17 #include<utility>
18 #include<functional>
19 #include<iomanip>
20 #include<sstream>
21 #include<ctime>
22 #include<cassert>
23 #define A first
24 #define B second
25 #define mp make_pair
26 #define pb push_back
27 #define pw(x) (1ll << (x))
28 #define sz(x) ((int)(x).size())
29 #define all(x) (x).begin(),(x).end()
30 #define rep(i,l,r) for(int i=(l);i<(r);i++)
31 #define per(i,r,l) for(int i=(r);i>=(l);i--)
32 #define FOR(i,l,r) for(int i=(l);i<=(r);i++)
33 #define eps 1e-9
34 #define PIE acos(-1)
35 #define cl(a,b) memset(a,b,sizeof(a))
36 #define fastio ios::sync_with_stdio(false);cin.tie(0);
37 #define lson l , mid , ls
38 #define rson mid + 1 , r , rs
39 #define ls (rt<<1)
40 #define rs (ls|1)
41 #define INF 0x3f3f3f3f
42 #define lowbit(x) (x&(-x))
43 #define sqr(a) a*a
44 #define ll long long
45 #define vi vector<int>
46 #define pii pair<int, int>
47 #define dd(x) cout << #x << " = " << (x) << ", "
48 #define de(x) cout << #x << " = " << (x) << "\n"
49 #define endl "\n"
50 using namespace std;
51 //**********************************
52 const int maxn=1e6+7;
53 vector<int>v;
54 int n,m,cnt,x,y,k;
55 int root[maxn],a[maxn];
56 struct Node{
57     int l,r,sum;
58     Node(){}
59     }T[maxn*40];
60 //**********************************
61 int getid(int x){return lower_bound(all(v),x)-v.begin()+1;}
62 void update(int l,int r,int &x,int y,int pos)
63 {
64     T[++cnt]=T[y],T[cnt].sum++,x=cnt;
65     if(l==r)return ;
66     int mid=l+r>>1;
67     if(mid>=pos)update(l,mid,T[x].l,T[y].l,pos);
68     else update(mid+1,r,T[x].r,T[y].r,pos);
69 }
70 int query(int l,int r,int x,int y,int k)
71 {
72     if(l==r)return l;
73     int mid=l+r>>1;
74     int sum=T[T[y].l].sum-T[T[x].l].sum;
75     if(sum>=k)return query(l,mid,T[x].l,T[y].l,k);
76     return query(mid+1,r,T[x].r,T[y].r,k-sum);
77 }
78 //**********************************
79 int main()
80 {
81     scanf("%d%d",&n,&m);
82     FOR(i,1,n)scanf("%d",&a[i]),v.pb(a[i]);
83     sort(all(v)),v.erase(unique(all(v)),v.end());
84     FOR(i,1,n)update(1,n,root[i],root[i-1],getid(a[i]));
85     FOR(i,1,m)scanf("%d%d%d",&x,&y,&k),printf("%d\n",v[query(1,n,root[x-1],root[y],k)]);
86     return 0;
87 }