731F - Video Cards - CodeForces Solution

#include<bits/stdc++.h>
#define int long long
#define pb push_back
#define pii pair<int, int>
#define F first
#define S second
#define all(x) x.begin(), x.end()
using namespace std;
const int N = 4e5+7;
int arr[N], cnt[N], mmz[N];
int32_t main(){
     ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
     int n; cin >> n;
     for(int i = 1; i <= n; i++) cin >> arr[i];
     for(int i = 1; i <= n; i++) cnt[arr[i]+1]++;
     for(int i = 2; i < N; i++) cnt[i] += cnt[i-1];
     int mx = 0;
     sort(arr+1, arr+n+1);
     for(int i = 1; i <= n; i++){
          int cmp = 0;
          if(mmz[arr[i]] > 0) continue;
          for(int j = arr[i]; j <= arr[i]*(arr[n]/arr[i]); j+=arr[i]){
               cmp += ((cnt[j+arr[i]] - cnt[j])*j);
          }
          mmz[arr[i]] = 1;
          mx = max(mx, cmp);
     }
     cout << mx;
}