Kakao New Graduate Recruitment: First Coding Test Problem Solutions and Passing Criteria Revealed

The problem solutions and passing criteria for Kakao's first coding test for new developer recruitment have been released. The exam was conducted online on September 16, and candidates must solve at least 4 out of 7 problems to pass the first round. All problems have equal point values with no partial credit, and the grading system is designed so that passing the input/output examples ensures passing the grading.

Statistics by Language and Code Characteristics

The most used language among applicants was Java (43%), followed by C++ (36%), Python (11%), and JavaScript (8%). The pass rate was highest for C++ (25%), followed by Python (24%). In contrast, Java, which had the most applicants, had a pass rate of 11%, while JavaScript had the lowest pass rate at 9%.

In terms of lines of code, C++ had the longest average code length, while Python solved the problems with the shortest code. Notably, problem 6, 'Friends 4 Block', required long code of over 80 lines in Java.

Key Problem Solutions and Difficulty Levels

• Blind Recruitment Characteristics: Instead of competition-style algorithm problems like ACM-ICPC, original problems assuming real-world scenarios were presented.
• Difficulty Distribution: Problems were arranged from easy to difficult, with accuracy rates gradually declining from the first problem (expected over 80%) to the last.
• Highest Difficulty Problem: The final problem, 'Traffic', required calculating the maximum throughput per second and had to be solved with O(n^2) or O(n log n) complexity using the sliding window technique. This problem had the lowest accuracy rate at 17.99%.
• Other Key Problems: Included calculating 'Jaccard Similarity' using 'multisets', implementing the LRU cache algorithm, and implementing the 2x2 block removal game logic.