566F - Clique in the Divisibility Graph - CodeForces Solution

#include <bits/stdc++.h>

using namespace std;

#define int long long
#define pb push_back
#define endl '\n'
#define f first
#define s second
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);

const int N = 1e6+5;
int arr[N];

int mod = 1000000007 ;

vector < int > vec ;
set < int > st ;
map < int, int > mp;


int32_t main()
{
    fast

    int T = 1 ;
    // cin >> T ;
    while(T--)
    {
       int n ; cin >> n ;

       for(int i=1 ; i <= n ; i++)
       {
           int x ;
           cin >> x ;
           arr[x] = 1 ;
       }

       int ans = 0 ;

       for(int i=1 ; i <= 1e6 ; i++)
       {
           for(int j= i + i ; j <= 1e6 ; j += i)
            if(arr[j]) arr[j] = max(arr[j] , arr[i] + 1) ;

           ans = max(ans , arr[i]);
       }

       cout << ans ;

    }
}