Medium data structure and algorithm practice puzzle.
Platforms sit in a row and reach[i] is how many platforms ahead you can jump from platform i. Starting on the first, return the fewest jumps to land on the last, or -1 if you can't. The greedy choice is to treat each jump as a range: everything reachable with j jumps. While walking through that range, track the farthest platform any of them reaches. That's where the range for j + 1 jumps ends. It's breadth-first search in disguise, with each range as one level.
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 Entity Bundle Builder, a pipeline you can run and download. See every Software Engineer project.
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