Medium data structure and algorithm practice puzzle.
Given a whole number, return it with its digits reversed and its sign kept. So 123 becomes 321, -45 becomes -54, and 100 becomes 1. Set the sign aside and work with the positive number. Grab the last digit with n mod 10, add it to the end of your result, then drop it from n. Put the sign back at the end.
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 Reading Sampler, a pipeline you can run and download. See every Software Engineer project.
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