Easy data structure and algorithm practice puzzle.
Given a number that's 0 or more, return its binary digits as an array. n mod 2 gives you the last bit, so put it at the front of the array, then halve n and round down. Repeat until n is 0. Since this builds from the right, each new bit goes in front. If n is 0 to begin with, return [0].
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 Order Flag Store, a pipeline you can run and download. See every Software Engineer project.
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