Medium data structure and algorithm practice puzzle.
Given a distribution tree and a starting TTL, return how many nodes get the packet. Each hop lowers the TTL by 1, and a packet with TTL 0 is dropped. So the root is reached if TTL is at least 1, its children if TTL is at least 2, and so on. Count a node, then recurse into its children with TTL - 1.
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.
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