Medium data structure and algorithm practice puzzle.
Given a sorted list of letters and a target letter, return the first letter that comes strictly after the target. If none do, wrap around and return the first letter. Binary search for the first letter bigger than the target, then use that index mod the list's length to handle the wrap.
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 Shot Ordered Index, a pipeline you can run and download. See every Software Engineer project.
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