11417 - GCD

11417 - GCD 

 Topic: GCD

Code:

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

typedef long long ll;

int main()
{

   //double start_time = clock();
    #ifndef ONLINE_JUDGE
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
  #endif
    int n;
    while(cin >> n && n){
      int ans = 0;
    for(int i = 1; i < n; i++){
      for(int j = i+1; j <= n; j++){
        ans += __gcd(i,j);
      }
    }
    cout << ans << endl;
  }

    return 0;
}

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