Codewars is an educational online platform for computer programming. On the platform, users aka "codewarriors" try to solve programming challenges known as "kata" to practice programming skills and gain honor points, which represent the level of respect a user has earned from the community. Each kata is set to a kyū rank, based on its subject area and difficulty. The harder the kata, the more points. Every new codewarrior is ranked as 8 kyū (Beginner) and can advance through the ranks by completing kata at or above their rank to reach the final 4th dan (Master). Kyū indicates the number of degrees away from the master level. This is why they count downward. Once you reach the master level, we count upward.
Codewars give you 12 seconds to complete all sample and random tests, so the code should be effiecient enough.