Medium data structure and algorithm practice puzzle.
Given a sorted array and a target, return the indices of the two numbers that add up to the target. Put one pointer at each end. If their sum is too small, move the left pointer right. If it's too big, move the right pointer left. Because the array is sorted, you never need a hash map, so it uses no extra memory.
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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