Medium data structure and algorithm practice puzzle.
Given a sorted array and a number d, return true if two different items are exactly d apart. Use two pointers that both move forward. If the gap between them is too small, move the right one. If it's too big, move the left one. Don't let them land on the same item.
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 Reading Throttle, a pipeline you can run and download. See every Software Engineer project.
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