Medium data structure and algorithm practice puzzle.
Given a messy file path like "/a/./b/../../c/", return the clean version, "/c". Split on "/" and use a stack of folder names. Skip empty pieces and ".". For "..", pop the last folder (if there is one). Push everything else. Then join the stack back together with a "/" in front.
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 Trip Syntax Gate, a pipeline you can run and download. See every Software Engineer project.
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