How do I implement negative numbers into this binomial coefficients method?

Question

private long binomial(int n, int k) {
    if (k == 0 || k == n) {
        return 1;
    } else if (k > n) {
        return 0;
    } else if (0 < k && k < n) {
        return binomial(n - 1, k - 1) + binomial(n - 1, k);
    }
    return 0;
}

Hi, does anyone know how I can implement negative numbers into the method I've got so far? The arguments which aren't satisfied are; k<0 , n=0 , n<0. I'm not sure how to implement these so I've placed 'return 0' as a placeholder.

The correct value/formula for each case. I'm not sure what the formula is for returning when k<0 etc. — Andrew Coates, Mar 05 '16 at 19:43
Not in the original but I guess that's what I need to a degree. From the link below, if I'm reading it correctly, returning 0 is correct? — Andrew Coates, Mar 05 '16 at 19:57
Then you could possibly close the question by accepting that answer. Ideally, posting a link as an answer is not acceptable and asking for a formula too is not considered as an ideal question on SO. — Mathews Mathai, Mar 05 '16 at 19:59
Sorry, I'm fairly new to SO. Guess I just needed clarification. Thanks! — Andrew Coates, Mar 05 '16 at 20:11

Southpaw · Answer 1 · 2016-03-05T20:02:00.437

2

Wolfram has an article discussing what happens when the numbers are negative:

http://mathworld.wolfram.com/BinomialCoefficient.html

Cases

edited Mar 05 '16 at 20:02

answered Mar 05 '16 at 18:54

Southpaw

43
5

This is not an answer. Please avoid posting links as answers. – Mathews Mathai Mar 05 '16 at 19:53
Sorry, I understand why it is not a good enough answer, but what is stopping me from just copying and pasting from the website? I thought I was doing a service by at least providing the source? – Southpaw Mar 05 '16 at 20:00
Yes. Ideally, your answer is supposed to be a comment. Since you don't have enough reputation to comment, you should avoid posting answers like this to maintain your reputation so that you get the privilege to comment. Don't worry. Downvotes indicate that your answer is not qualified enough to appear here. No offence. – Mathews Mathai Mar 05 '16 at 20:04
Okay, Thanks! It appears the OP found it useful to a degree, though. – Southpaw Mar 05 '16 at 20:07

How do I implement negative numbers into this binomial coefficients method?

1 Answers1