Debugging & Refactoring

Most candidates prepare for Chewy as if the loop were four rounds of writing fresh code from a blank editor. One of the rounds is not that. You are handed a program that already runs, or nearly does. You're asked to make it correct, faster, or readable, then to back your changes with test cases that show the requirements are met. It shows up on the schedule under names like "debugging" or "debugging and refactoring," and it is the round almost nobody trains for.

That is why it earns an hour of your prep. The algorithms are not the hard part here. The grade covers whether you can read someone else's code and find where it diverges from the spec. Then you change the smallest thing that fixes it and convince a skeptical interviewer with a handful of well-chosen inputs. Engineers who ship every day do this constantly. Chewy built a round to watch you do it live.