Follow up questions: What if the radius of neighbors will be dynamic (not 1, but 2, 3, etc)? I implemented a loop for this, but they said (in feedback): "Was not able to code it dynamically just with different levels". IDK what they had in mind. Code complexity (n^2 or n*m). I was nervous and said it's n^m instead of n*m. (realized mistake after the interview ended) Can you improve time complexity? Rules contain 2 matrices (previous state and new state). I assumed the function will receive a matrix as well and I said it's not possible to improve with current input/rules. Then they told me that input CAN BE different from rules and I can receive an array of "alive" cells. Just wow. Interviewers were not friendly at all (only in the first few minutes talking about their position at Booking). They gave you a task and were sitting like "Do what you want. We don't care." After I implemented the function, they just started throwing follow up questions and pressure me to give the correct solution in the same second (no time to think). It was not a Backend Interview. It was a stress-test: "give us correct and best solution right now or you will not pass"