Medium data structure and algorithm practice puzzle.
Given two points (x0, y0) and (x1, y1) and an x, return the y on the straight line between them, rounded to 3 decimals. Work out how far x is from x0 to x1 as a fraction, then move that fraction of the way from y0 to y1. This is the same lerp behind every animation and color fade.
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 Event Forecaster, a pipeline you can run and download. See every Software Engineer project.
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