Medium data structure and algorithm practice puzzle.
Given [filedDay, limitDays, today], return how many days are left before the deadline. The deadline is filedDay plus limitDays, so subtract today from that. If the deadline has passed, the answer is negative. Date libraries do the same thing underneath, counting days as plain numbers.
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 Audit Trail, a pipeline you can run and download. See every Software Engineer project.
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