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Iteration / RecursionSolved Oct 27, 2025
Problem
Given a non-negative integer N, calculate its factorial, denoted N!. N! is the product of all positive integers less than or equal to N. (0! = 1).
Reading the solution first feels like progress, but it makes the next similar problem — and the interview version — much harder, because you skipped the part where you figure it out. Give it an honest 20–30 minutes. Stuck? Re-read the pattern, watch the concept video, or try the brute force first.
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