Medium data structure and algorithm practice puzzle.
Given a step, the number of warmup steps, the total steps, and a base learning rate, return the rate at that step, rounded to 6 decimals. During warmup, ramp straight up from 0 to the base rate. After warmup, work out how far through the rest you are, as a fraction p, and return 0.5 x base x (1 + cos(pi x p)).
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 Request Smoothing Rig, a pipeline you can run and download. See every Software Engineer project.
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