Medium data structure and algorithm practice puzzle.
Given your rating and deviation, the puzzle's rating and deviation, and whether you solved it, return your new rating, rounded to two decimal places. Compare what happened with what the ladder expected, weight it by how sure the ladder is, and move by that much. For a settled player this lands within about a point of the real ladder. Brand new accounts get an extra correction this puzzle skips.
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 Match Smoothing Rig, a pipeline you can run and download. See every Software Engineer project.
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