1915D - Unnatural Language Processing - CodeForces Solution

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

#define opt() ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl '\n'
#define ll long long
#define ld long double
int main()
{
    opt();
    ll t;
    cin>>t;

    while(t--)
    {
        ll n;
        cin>>n;
        string s;
        cin>>s;
        string ans="";
        for(ll i=n-1;i>=0;)
        {
            if(s[i]=='a' || s[i]=='e')
            {
                for(ll j=i;j>=i-1;j--)
                {
                    ans+=s[j];
                }
                i-=2;
            }
            else
            {
                for(ll j=i;j>=i-2;j--)
                {
                    ans+=s[j];
                }
                i-=3;
            }
            ans+='.';
        }
        ans.pop_back();
        reverse(ans.begin(),ans.end());
        cout<<ans<<endl;
    }
}