Hard data structure and algorithm practice puzzle.
Given a single qubit's real amplitudes [a, b], apply a Hadamard gate and return the new amplitudes, rounded to 4 decimals. The new values are (a + b) / sqrt(2) and (a - b) / sqrt(2). Starting from [1, 0], you get an even split between 0 and 1. That's how a qubit gets into superposition.
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 Shot Stream Buffer, a pipeline you can run and download. See every Software Engineer project.
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