Hard data structure and algorithm practice puzzle.
Given an array and a window size k, return the biggest number in every run of k numbers in a row. So [1, 3, -1, -3, 5, 3, 6, 7] with k = 3 gives [3, 3, 5, 5, 6, 7]. Slide the window one step at a time and find the max of each one. Follow-up: a monotonic deque gets this down to one pass.
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 Sample Anomaly Watch, a pipeline you can run and download. See every Software Engineer project.
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