Medium data structure and algorithm practice puzzle.
Given a list of labels, return the Shannon entropy in bits, rounded to 3 decimals. Count each label and turn the counts into probabilities p. The entropy is the sum of -p x log2(p). A group with one label scores 0, and an even split between two labels scores 1. Decision trees split wherever this drops the most.
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 Hot Sample Monitor, a pipeline you can run and download. See every Software Engineer project.
Browse all 576 puzzles