Medium data structure and algorithm practice puzzle.
Given a batch of numbers, normalize them to a mean of 0 and a spread of 1, rounded to 3 decimals. Find the mean and variance, then for each value, subtract the mean and divide by the square root of (variance + 0.00000001). That tiny number matters: if every value is the same, the variance is 0 and you'd divide by zero.
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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