Luogu3834 【模板】可持久化线段树 1（主席树）

区间第k大裸题，开始的错误代码竟然A了

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#define R(a,b,c) for(register int  a = (b); a <= (c); ++ a)
#define nR(a,b,c) for(register int  a = (b); a >= (c); -- a)
#define Max(a,b) ((a) > (b) ? (a) : (b))
#define Min(a,b) ((a) < (b) ? (a) : (b))
#define Fill(a,b) memset(a, b, sizeof(a))
#define Abs(a) ((a) < 0 ? -(a) : (a))
#define Swap(a,b) a^=b^=a^=b
#define ll long long

//#define ON_DEBUG

#ifdef ON_DEBUG

#define D_e_Line printf("\n\n----------\n\n")
#define D_e(x)  cout << #x << " = " << x << endl
#define Pause() system("pause")
#define FileOpen() freopen("in.txt","r",stdin);

#else

#define D_e_Line ;
#define D_e(x)  ;
#define Pause() ;
#define FileOpen() ;

#endif

struct ios{
    template<typename ATP>ios& operator >> (ATP &x){
        x = 0; int f = 1; char c;
        for(c = getchar(); c < '0' || c > '9'; c = getchar()) if(c == '-')  f = -1;
        while(c >= '0' && c <= '9') x = x * 10 + (c ^ '0'), c = getchar();
        x*= f;
        return *this;
    }
}io;
using namespace std;

const int N = 200007;

int treeIndex;
int sum[N<<5], T[N], L[N<<5], R[N<<5];

inline void Build(int &rt, int l, int r){
    rt = ++treeIndex;
    if(l == r) return;
    int mid = (l + r) >> 1;
    Build(L[rt], l, mid), Build(R[rt], mid + 1, r);
}

inline void Updata(int &root, int rt, int l, int r, int x){
    root = ++treeIndex;
    L[root] = L[rt], R[root] = R[rt];
    sum[root] = sum[rt] + 1;
    if(l == r) return;
    int mid = (l + r) >> 1;
    if(x <= mid)
        Updata(L[root], L[rt], l, mid, x);
    else
        Updata(R[root], R[rt], mid + 1, r, x);
}

inline int Query(int u, int v, int l, int r, int K){
    if(l == r) return l;
    int mid = (l + r) >> 1, x = sum[L[v]] - sum[L[u]];
    if(x >= K)
        return Query(L[u], L[v], l, mid, K);
    else
        return Query(R[u], R[v], mid + 1, r, K - x);
}

int a[N], b[N];
int main(){
    //FileOpen();
    
    int n, Ques;
    io >> n >> Ques;
    R(i,1,n){
    	io >> a[i];
    	b[i] = a[i];
    }
    
    sort(b + 1, b + n + 1);
    int m = unique(b + 1, b + n + 1) - b - 1;
    
    Build(T[0], 1, m);
    R(i,1,n){
    	int pos = lower_bound(b + 1, b + m + 1, a[i]) - b;
    	Updata(T[i], T[i - 1], 1, m, pos);
    }
    while(Ques--){
    	int l, r, K;
    	io >> l >> r >> K;
        printf("%d\n", b[Query(T[l-1], T[r], 1, m, K)]);
    }
    return 0;
}