Easy data structure and algorithm practice puzzle.
Given an array of days left until each deadline, return how many are overdue. A negative number means the deadline has passed. Zero means it's due today, so it doesn't count. Walk the array once and count the values below 0. Getting that zero right is the whole puzzle.
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 Clause Stats Roll-up, a pipeline you can run and download. See every Software Engineer project.
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