Easy data structure and algorithm practice puzzle.
A recorded sound effect has silence at both ends, which delays it when it plays. Given its samples and a threshold, return [first, last], the indexes of the first and last samples louder than the threshold, or [-1, -1] if none are. Loudness is the absolute value, since sound waves swing below zero as well as above it. Use two pointers, one walking in from each end until it finds something loud.
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 Entity Burst Detector, a pipeline you can run and download. See every Software Engineer project.
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