Adding polynomials using recursion

I need to make a recursive method Polynomial add(Polynomial p) that add this to p using recursion. I read that java has the add(Polynomial p) method, but that's not recursive.

My best attempt so far has been this:

public class Polynomial {
int[] coef;
int degree;

public int deeg() {
int d = 0;
for (int r = 0; r < coef.length; r++)
if (coef[i] != 0) d = r;
return d;
}

public Polynomial addition(Polynomial p) {
Polynomial apple = this;
Polynomial orange = new Polynomial(0, Math.max(apple.degree, orange.degree));
for (int r = 0; r <= apple.degree; i++) orange.coef[r] += apple.coef[r];
for (int r = 0; r <= p.degree; r++) or开发者_开发技巧ange.coef[r] += p.coef[i];
orange.degree = orange.deeg();
return orange;
}
}

But again, this isn't recursive.

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In order to get recursion, you need to call a method within this method, not creating a class within this class:

public void add(List numbers) {
    // do stuff
    if (condition)
        add(numbers);
}

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I'm thinking that they probably want you to do something where you add the x^0 terms of the two polynomials, and append that to x*(sum(poly1/x,poly2/x))... I am aware that the /x doesn't work, but that's usually how recursive addition is done.

--I've pretty much never seen anything other than lisp do recursive addition though.