Kakao Releases Problem Explanations for the 2022 New Graduate Recruitment Second Coding Test

Kakao has released the problem explanations for the second coding test of the 2022 KAKAO BLIND RECRUITMENT, which was conducted on September 25, 2021. This test focused on implementing a game matching system similar to real-world business scenarios and lasted for 4 hours and 45 minutes. Candidates had to try various strategies to resolve the trade-off between accuracy and efficiency. Key approaches introduced included immediate matching from the queue, matching between users with similar scores, general strategies reflecting game time and win/loss records, and the ELO rating system used by organizations such as the World Chess Federation. Additionally, methods to handle abusers (users intentionally losing), who account for approximately 5% of all users, were suggested, such as ignoring records with game times of 10 minutes or less or utilizing a blacklist. In terms of optimization, it was analyzed that strategies minimizing ChangeGrade API calls to shorten simulation time were effective.