Atlassian Coding Question: URL Router with Wildcards

You are asked to build a deterministic, thread-safe URL router that maps registered path patterns to handlers and returns any captured parameters. The router matches path segments (slash-separated) and must support two segment-level constructs: a single-segment wildcard (*) that matches exactly one segment, and named parameters (like :id) that match one segment and capture its value. When multiple patterns match, the router must pick the pattern that was registered first (first-registered wins).

In an interview you'll typically walk through these stages: parsing a pattern into segments, inserting the pattern into a lookup structure, and implementing a resolve operation that walks the structure to find the best match and assemble a parameter map. You should describe and justify the data structure you choose (a segment trie or prefix tree is common), how you handle ties deterministically, and how you parse and validate incoming URLs.

Skill signals interviewers look for: robust string parsing and edge-case handling (empty segments, trailing slashes), deterministic matching logic, clear API design for register/resolve, and concurrency control that preserves registration order. For concurrency you can propose coarse-grained locking, reader-writer locks, or copy-on-write registration to allow lock-free resolves while keeping registration order consistent. Mention complexity (insert/resolve ~O(S) for S segments), memory trade-offs, and a few unit tests and edge cases you would write to prove correctness.