Medium data structure and algorithm practice puzzle.
Given a list of numbers, return each one's z-score, rounded to 3 decimals. Find the mean and the standard deviation (dividing by n). Then for each value, subtract the mean and divide by the standard deviation. If every value is the same, the deviation is 0, so treat it as 1. The result has a mean of 0 and a spread of 1.
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 Sample Calibrator, a pipeline you can run and download. See every Software Engineer project.
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