Medium data structure and algorithm practice puzzle.
Given a list of MIDI notes and a target note, return how many notes are the same pitch as the target, in any octave. Compare each note mod 12 with the target mod 12, and count the matches. Every C, high or low, comes out as 0, so they all match each other.
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 Track Integrity Check, a pipeline you can run and download. See every Software Engineer project.
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