主席树板子

int n,q;
int tot;
#define ls ch[rt][0]
#define rs ch[rt][1]
#define vl ch[vs][0]
#define vr ch[vs][1]
int rt[M];
int ch[M<<5][2];
int val[M<<5];
int a[M],b[M];
int m;
int qr(int x){
    return (lower_bound(b,b+m,x) - b) +1 ;
}
int qr(int rt,int vs,int l,int r,int k){
    if(l==r)return l;
    int mid = l+r>>1;
    int v= val[ls] - val[vl];
    if(k<=v)return qr(ls,vl,l,mid,k);
    else return qr(rs,vr,mid+1,r,k-v);
}
void upd(int &rt,int vs,int l,int r,int k){
    rt=++tot;
    ls=vl;
    rs=vr;
    val[rt]=val[vs]+1;
    if(l==r)return;
    int mid=l+r>>1;
    if(k<=mid)upd(ls,vl,l,mid,k);
    else upd(rs,vr,mid+1,r,k);
}

void solve(){
    cin>>n>>q;
    rep(i,1,n){
        cin>>a[i];
        b[i-1]=a[i];
    }
    sort(b,b+n);
    m =unique(b,b+n) - b;
    rep(i,1,n){
        upd(rt[i],rt[i-1],1,n,qr(a[i]));
    }

    rep(i,1,q){
        int l,r,k;cin>>l>>r>>k;
        cout<<b[qr(rt[r],rt[l-1],1,n,k)-1]<<endl;
    }
}