Easy data structure and algorithm practice puzzle.
Given the validation loss after each epoch and a patience number, return the epoch where training should stop, or -1 if it never does. Track the best loss so far. Every epoch that doesn't beat it adds one to a counter, and a new best resets it to 0. When the counter reaches patience, stop and return that epoch's index.
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 Billing Run, a pipeline you can run and download. See every Software Engineer project.
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