2 Factorial
Problem Statement
Calculate the Factorial of a Positive Number Using Recursion.
The factorial of a non-negative integer N, denoted as N!, is the product of all positive integers less than or equal to N. The factorial of 0 is defined as 1.
Here is what the example input/output looks like:
| Input | Expected Output | Explanation |
|---|---|---|
| Number = 5 | Factorial = 120 | The factorial of 5 is calculated as 5 _ 4 _ 3 _ 2 _ 1 = 120. |
| Number = 7 | Factorial = 5040 | The factorial of 7 is calculated as 7 _ 6 _ 5 _ 4 _ 3 _ 2 _ 1 = 5040. |
| Number = 1 | Factorial = 1 | The factorial of 1 is 1 itself. |
Try it yourself
Try solving this question here:
🎯 STRICT STANDOUT — Problem cue: Factorial
1. Why
n! linear recursion with multiply combine. Interview value: 0!=1, int overflow, stack vs loop.
2. Big-O (K11)
T(n)=T(n-1)+Θ(1) → Θ(n) time, Θ(n) stack; 5!=1203. Pattern + when-NOT
LINEAR RECURSION. When-NOT: iterative multiply Θ(1) space; BigInteger for large n.
4. Edge
0!→1; 1!→1; 12! fits int; 13! overflows signed 32-bit; neg undefined5. Panel
Q: Base 0 or 1? A: 0! defined 1; also stops path.
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