Medium data structure and algorithm practice puzzle.
Given a list of [start, end] events, return the most you can attend without any overlap. One event can start right when another ends. Sort by EARLIEST END, not earliest start and not shortest. Then take every event that starts after your last one ended. Finishing as early as possible leaves the most room for everything after.
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 Login Budget Allocator, a pipeline you can run and download. See every Software Engineer project.
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