rt，本地没问题，但交上去WA了两个点，求助

#include <bits/stdc++.h>

using namespace std;

inline int read(){
	int x=0,f=1;char ch=getchar();
	while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();}
	while(isdigit(ch)){x=(x<<3)+(x<<1)+(ch&15);ch=getchar();}
	return x*f;
}

const int N=2e5;
const int SIZE=N*64;

int n,m;
int arr[N];
int sta[N],top;

#define _L -0x3f3f3f3f
#define _R 0x3f3f3f3f
#define mid ((l+r)>>1)

namespace WST{
	
	struct TREE{
		int ls,rs,sum;
	}tree[SIZE];
	int CNT,rt[N];

	inline void pushUp(int root){
		tree[root].sum=tree[tree[root].ls].sum+tree[tree[root].rs].sum;
	}

	void update(int &root,int l,int r,int pos,int sum){
		if(!root) root=++CNT;
		if(l==r){tree[root].sum+=sum;return;}
		pos<=mid?update(tree[root].ls,l,mid,pos,sum):update(tree[root].rs,mid+1,r,pos,sum);
		pushUp(root);
	}

	int kth(int root,int l,int r,int k){
		if(tree[root].sum<k) return -1;
		if(l==r) return l;
		return k<=tree[tree[root].ls].sum?kth(tree[root].ls,l,mid,k):kth(tree[root].rs,mid+1,r,k-tree[tree[root].ls].sum);
	}

	void merge(int &Address,int x,int y,int l,int r){
		if(!x||!y){
			Address=x|y;
			return;
		}
		if(!Address) Address=++CNT;
		if(l==r){
			tree[Address].sum=tree[x].sum+tree[y].sum;
			return;
		}
		merge(tree[Address].ls,tree[x].ls,tree[y].ls,l,mid);
		merge(tree[Address].rs,tree[x].rs,tree[y].rs,mid+1,r);
		pushUp(Address);
		return;
	}
	
}

struct TREE{
	int ls,rs;
	int val;//在权值线段树上的编号
}tree[N<<4];
int CNT,rootOfSegtree;

inline void pushUp(int root){
	WST::merge(tree[root].val,tree[tree[root].ls].val,tree[tree[root].rs].val,_L,_R);
}

void build(int &root,int l,int r){
	if(!root) root=++CNT;
	if(l==r){
		tree[root].val=WST::rt[l];
		return;
	}
	build(tree[root].ls,l,mid);build(tree[root].rs,mid+1,r);//cout<<"root:"<<l<<' '<<r<<endl;
	pushUp(root);
}

void getTheTrees(int root,int l,int r,int Ql,int Qr){
	if(Ql<=l&&r<=Qr){
		sta[++top]=tree[root].val;
		return;
	}
	Qr<=mid?getTheTrees(tree[root].ls,l,mid,Ql,Qr):\
	(Ql>=mid+1?getTheTrees(tree[root].rs,mid+1,r,Ql,Qr):\
	(getTheTrees(tree[root].ls,l,mid,Ql,Qr),getTheTrees(tree[root].rs,mid+1,r,Ql,Qr)));
}

int query(int l,int r,int k){
	if(l==r) return l;
	int sum=0;
	for(int i=1;i<=top;i++) sum+=WST::tree[WST::tree[sta[i]].ls].sum;
	for(int i=1;i<=top;i++) sta[i]=k<=sum?WST::tree[sta[i]].ls:WST::tree[sta[i]].rs;
	return k<=sum?query(l,mid,k):query(mid+1,r,k-sum);
}

#undef mid

void init(){
	for(int i=1;i<=n;i++)
		WST::update(WST::rt[i],_L,_R,arr[i],1);
	build(rootOfSegtree,1,n);
}

int calc(int l,int r,int k){
	top=0;
	getTheTrees(rootOfSegtree,1,n,l,r);
	return query(_L,_R,k);
}

#undef _L
#undef _R

int main(){
//	freopen("in","r",stdin);
//	freopen("out","w",stdout);
	n=read(),m=read();
	for(int i=1;i<=n;i++) arr[i]=read();
	
	init();

	int l,r,k;
	for(int i=1;i<=m;i++){
		l=read(),r=read(),k=read();
		printf("%d\n",calc(l,r,k));
	}
	return 0;
}