Medium data structure and algorithm practice puzzle.
Given a sorted array that was rotated, return how many places it was rotated. That's just the index of the smallest value. Find it with binary search: compare the middle with the right end. If the middle is bigger, the smallest is to the right. Otherwise, it's at mid or to the left.
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 Sorted Store, a pipeline you can run and download. See every Software Engineer project.
Browse all 576 puzzles