`int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
#ifndef ONLINE_JUDGE
freopen("input.txt","r",stdin);
freopen("output.txt","w",stdout);
#endif
ll t;
cin>>t;
while(t--)
{
  ll n,i,sum=0,c,ma=0;
  ll arr[200005];
  ll freq[200005]={0};
  cin>>n;
  for(i=0;i<n;i++)
  {
    cin>>arr[i];
    if(arr[i]>ma)
      ma=arr[i];
    freq[arr[i]]++;
  }
  sort(freq,freq+ma+1);
  freq[ma+1]=mod;
  for(i=ma;i>=1;i--)
  {
if(freq[i]>=freq[i+1])
  freq[i]=freq[i+1]-1;

if(freq[i]>0)
sum=sum+freq[i];
else
break;
}
cout<<sum<<"n";

}` -TLE submission

 int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
#ifndef ONLINE_JUDGE
freopen("input.txt","r",stdin);
freopen("output.txt","w",stdout);
#endif
ll t;
cin>>t;
while(t--)
{
  ll n,i,sum=0,c,ma=0;
  cin>>n;
    ll arr[n+3];
  ll freq[n+3]={0};
  for(i=0;i<n;i++)
  {
    cin>>arr[i];
    if(arr[i]>ma)
      ma=arr[i];
    freq[arr[i]]++;
  }
  sort(freq,freq+ma+1);
  freq[ma+1]=mod;
  for(i=ma;i>=1;i--)
  {
    if(freq[i]>=freq[i+1])
      freq[i]=freq[i+1]-1;

    if(freq[i]>0)
  sum=sum+freq[i];
else
  break;
  }
  cout<<sum<<"n";

}
}
AC Submission