Medium data structure and algorithm practice puzzle.
Given an array of order totals, return the average, rounded. Add them up and divide by how many there are. Before you write the division, decide what an empty list should return, because that's the one case where this breaks.
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 Order Stream Buffer, a pipeline you can run and download. See every Software Engineer project.
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