Shared code

/* God is Great !
    Author : SANIDHIYA*/
#include<bits/stdc++.h> 
using namespace std;
set<int> combine(set<int> a, set<int> b){
    set<int> c;
    for(auto elem : a) c.insert(elem);
    for(auto elem : b) c.insert(elem);
    return c;
}
set<int> identity(){
    set<int> temp;
    return temp;
}
template<class T,T(*combine) (T,T),T(*identity)()>
class SegmentTree{
    private : 
    int n;
    T *t;

    void build(vector<T> &a, int v, int tl, int tr) {
        if (tl == tr) {
            t[v] = a[tl];
        } else {
            int tm = (tl + tr) / 2;
            build(a, v*2, tl, tm);
            build(a, v*2+1, tm+1, tr);
            t[v] = combine(t[v*2],t[v*2+1]);
        }
    }
    
    T run_query(int v, int tl, int tr, int l, int r) {
    if (l > r) 
        return identity();
    if (l == tl && r == tr) {
        return t[v];
    }
    int tm = (tl + tr) / 2;
    return combine(run_query(v*2, tl, tm, l, min(r, tm))
           ,run_query(v*2+1, tm+1, tr, max(l, tm+1), r));
    }


    void run_update(int v, int tl, int tr, int pos, int new_val) {
    if (tl == tr) {
        t[v] = new_val;
    } else {
        int tm = (tl + tr) / 2;
        if (pos <= tm)
            run_update(v*2, tl, tm, pos, new_val);
        else
            run_update(v*2+1, tm+1, tr, pos, new_val);
        t[v] = combine(t[v*2],t[v*2+1]);
    }
    }   

    public: 

    SegmentTree(vector<T> &a){
        this->n = a.size();
        this->t = new T[4*(n + 1)];
        build(a, 1, 0, n-1);
    }
    T query(int l, int r){
        return run_query(1, 0, n-1, l, r);
    }

    void update(int pos, T new_val){
        run_update(1, 0, n-1, pos, new_val);
    }
    
    
};
void solve()
{
    vector<set<int>> temp(int(2e5 + 5));
    int n, q;
    cin >> n >> q;
    for(int i = 1; i <= n ; i++ ){
        int t;
        cin >> t;
        temp[i].insert(t);
    }
    SegmentTree<set<int>, combine, identity> sg(temp);
    while(q--){
        int l, r;
        cin >> l >> r;
        cout<<sg.query(l,r).size()<<"\n";
    }
 
}
int main()
{
ios_base::sync_with_stdio(false);
cout.tie(NULL);
cin.tie(NULL);
solve();
return 0;
}