Medium data structure and algorithm practice puzzle.
Given two sorted lists, merge them into one sorted list. Keep a pointer at the front of each. Take the smaller value, add it to the result, and move that pointer forward. When one list runs out, add the rest of the other. This is the merge step in merge sort, and databases use it to combine sorted data on disk.
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 Shot Burst Detector, a pipeline you can run and download. See every Software Engineer project.
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