Medium data structure and algorithm practice puzzle.
Given an array and k, return the k values that show up most often, most frequent first. Count every value in a hash map. Then sort the values by their counts from high to low and take the first k. If two values tie, keep the one that showed up first. Every trending list works like this.
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 Read Billing Run, a pipeline you can run and download. See every Software Engineer project.
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