How would you write a non-recursive algorithm to calculate factorials?

Question

How would you write a non-recursive algorithm to compute n!?

Answer 1

public double factorial(int n) {
    double result = 1;
    for(double i = 2; i<=n; ++i) {
        result *= i;
    }
    return result;
}

Answer 2

Rewrite the recursive solution as a loop.

Answer 3

I would use memoization. That way you can write the method as a recursive call, and still get most of the benefits of a linear implementation.

Answer 4

long fact(int n) {
    long x = 1;
    for(int i = 1; i <= n; i++) {
        x *= i;
    }
    return x;
}