Lonsgest Increasing Subsequence in nlogn

#include<bits/stdc++.h>
using namespace std;

#define fast ios_base::sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL)
#define ll long long
#define ld long double
#define pb push_back
#define fe first
#define se second
#define nl "\n"
#define pp pair < ll , ll >
#define sz(x) (ll)x.size()
#define st(x) sort(x.begin(),x.end())
#define rst(x) sort(x.rbegin(), x.rend())
#define all(x) x.begin(),x.end()
long double pi = 3.14159265358979323;

const double EPS = 1e-12;
const int N = 1e6 + 5;
const int mod = 1e9 + 7;

//Day1

//Printing Longest Increasing Subsequence in nlogn

int main()
{
    fast;
    ll t = 1;
    //cin >> t;
    while(t--){
    ll n;
    cin >> n ;
    ll a[n];
    for(int i = 0 ; i < n ;i++ ){
        cin >> a[i];
    }
    vector < pair < ll,  ll > > v;
    v.pb({a[0],0});
    vector < ll > prevind(n , -1);
    ll h[n];
    for(int i = 0 ; i < n ;i++ ){
            h[i] = 1;
    }
    //memset(h , 0 , sizeof(h));
    for(int i = 1 ; i < n ;i++ ){
       // cout << a[i] << " ";
        pair < ll , ll > p = {a[i] , -1};
        ll j = lower_bound(v.begin() , v.end() ,p) - v.begin();
        //cout << j << "\n";
        if(j == 0){
            v[j] = {a[i] ,i};
        }
        else if(j == sz(v)){
            prevind[i] = v[j - 1].se;
            v.pb({a[i],i});
            h[i] += h[v[j-1].se];
        }
        else{
            prevind[i] = v[j - 1].se;
            v[j] = {a[i] , i};
            h[i] += h[v[j-1].se];
        }
       // cout << h[i] << "\n";
    }

    ll maxm = 0 ;
    ll ind = 0 ;
    for(int i = 0 ; i < n ;i++ ){
            if(maxm < h[i]){
                maxm = h[i];
                ind = i;
            }
    }
    cout << maxm << "\n";
   /* cout << a[ind] << " ";
    while(prevind[ind] != -1){
        ind = prevind[ind];
        cout << a[ind] << " ";
    }
    cout << "\n";*/
    }























    return 0;

}