First Bad Version
Software Deployment Bug Tracker You're managing software releases. A bug was introduced in version X, causing all versions from X onward to fail. Given n total versions, find the first bad version using the minimum number of API calls. Example: n = 5, bad = 4 → 4 (versions 4 and 5 are bad)
Binary search is the tool here, but the real test is whether your invariant stays crisp. It's a great warm-up that builds boundary precision without a ton of moving parts. Interviewers care more about airtight boundaries than speed here.
Meet Coco
Coco is an AI study partner, not a person. She listens while you explain your code, asks what a line does and never hands you the fix. Sign in free to type with Coco, up to a daily limit, and to talk with her for one hour. After that, talking comes with the $79 pack. Anyone can open the editor and run their code.