只过了前两个点。

#include <bits/stdc++.h>//喵内～
#define int long long
#define re register//喵内～
using namespace std;//喵内～
typedef long long ll;
typedef long double ld;
const int N = 3e5 + 5;//喵内～要填数字哟～
inline int read(){
    int s = 0,f = 1;char c = getchar();
    while (!isdigit(c)){if (c == '-')f = -1;c = getchar();}
    while (isdigit(c)){s = (s<<3) + (s<<1) + (c ^ 48);c = getchar();}
    return s * f;
}//喵内～
int n,m;
int a[N],bucket[N],len;
struct SegmentTree{
    int cnt,root[N];
    struct node{
        int l,r,val;
    }tree[N << 5];
    int Newnode(){
        return ++cnt;
    }
    void pushup(int rt){
        tree[rt].val = tree[tree[rt].l].val + tree[tree[rt].r].val;
    }
    void build(int &rt,int l,int r){
        if (!rt)
            rt = Newnode();
        tree[rt] = (node){0,0,0};
        if (l == r){return;}
        int mid = (l + r) >> 1;
        build(tree[rt].l,l,mid);
        build(tree[rt].r,mid+1,r);
    }
    void update(int pre,int &rt,int l,int r,int pos){
        if (!rt)
            rt = Newnode();
        tree[rt].val = tree[pre].val + 1;
        if (l == r){
            return ;
        }
        int mid = (l + r) >> 1;
        if (pos <= mid)
            tree[rt].r = tree[pre].r,update(tree[pre].l,tree[rt].l,l,mid,pos);
        if (pos > mid)
            tree[rt].l = tree[pre].l,update(tree[pre].r,tree[rt].r,mid+1,r,pos);
        //pushup(rt);
    }
    int query(int pre,int rt,int l,int r,int k){
        if (l == r)
            return l;
        int v = tree[tree[rt].l].val - tree[tree[pre].l].val;
        int mid = (l + r) >> 1;
        if (k > v)
            return query(tree[pre].r,tree[rt].r,mid+1,r,k - v);
        else return query(tree[pre].l,tree[rt].l,l,mid,k);
    }

}Tree;
signed main(){
    n = read(); m = read();
    for (int i=1;i<=n;i++){
        a[i] = read();
        bucket[i] = a[i];
    }
    sort(bucket+1,bucket+n+1);
    len = unique(bucket+1,bucket+n+1) - bucket - 1;
    Tree.build(Tree.root[0],1,len);
    for (int i=1;i<=n;i++)
        Tree.update(Tree.root[i-1],Tree.root[i],1,len,lower_bound(bucket+1,bucket+len+1,a[i]) - bucket);
    sort(a+1,a+n+1);
    for (int i=1;i<=m;i++){
        int l,r,k;
        l = read(); r = read(); k = read();
        printf("%lld\n",a[Tree.query(Tree.root[l-1],Tree.root[r],1,len,k)]);
    }
    return 0;
}//喵内～
/*
*/