I need help with the helper method! Another person who helped me gave me this for the helper method but it's wrong. I kept getting stack overflow error. the error happens at return helper(n-1, n*partial)

if (n == 0) return partial; return helper(n - 1, n * partial);

*** CODE BELOW ***

/** * Two implementations of the factorial function. * This is just a place holder class for the two functions * * @author Charles Hoot * @version 4.0 */ public class RecursiveFactorial {

/** * The basic recursive factorial. * * @param n The number to compute factorial of. * @return n factorial. */ public long basic(long n) { long result = 1; if (n > 1) result = n*basic(n-1); return result; } /** * The tail recursive version of factorial. * * @param n The number to compute factorial of. * @return n factorial. */ public long tailRecursive(long n) { // IMPLEMENT THIS METHOD USING THE RECURSIVE HELPER FUNCTION // AND RETURN SOMETHING APPROPRIATE return 0; }

/** * The tail recursive helper function for factorial. * * @param n The number to compute factorial of. * @param partial The partial result that is being built up. * @return n factorial. */

private long helper(long n, long partial) { long result = 0; // IMPLEMENT THIS TAIL RECURSIVE METHOD return result; }

}