Factorial with Recursion
Practice writing a recursive function with a clear base case and recursive case.
Given a non-negative integer n, return n! (n factorial), defined as the product of all positive integers up to n, with 0! = 1.
Implement this recursively. This is a basics exercise for recursion itself — the goal is to internalize the shape every recursive function shares, not to find the fastest way to multiply numbers.
Example 1
Input: n = 5
Output: 120
Explanation: 5! = 5 * 4 * 3 * 2 * 1 = 120.
Example 2
Input: n = 0
Output: 1
Explanation: By definition, 0! = 1.
Example 3
Input: n = 1
Output: 1
Constraints
- 0 <= n <= 12
Follow-up
Can you rewrite this iteratively, without recursion? Which version would you actually ship?
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