Hard data structure and algorithm practice puzzle.
Given a list of matters, each with a list of party names, return true if any party shows up in two different matters. Keep a hash set of every party you've seen. For each matter, remove its duplicates first, so a name listed twice in the same matter doesn't count. Then check each name against the set. Return true at the first repeat.
Solve it three ways: snap the jigsaw pieces together, fill in the blanks, or type it from scratch against the tests. This one is free.
Every line of the solution comes with a note explaining why it is there, and a step by step replay shows the code running. At level 3, where you type it yourself, you can ask for an AI mock interview on this problem that ends with a hiring manager's scorecard.
Then grow it into a real project with the Software Engineer button: this puzzle becomes the Hot Clause Monitor, a pipeline you can run and download. See every Software Engineer project.
Browse all 576 puzzles