### LANGUAGE: JAVA

### CHALLENGE:

QUESTION 1:

The “odd/even factorial” of a positive integer n is represented as n!! and is defined non-recursively as: (n)(n-2)(n-4)…(4)(2) if n is even and is (n)(n-2)(n-4)…(5)(3) (1) if n is odd. What are the respective values of 6!! and 9!! ?

A) 48 and 945

B) 24 and 315

C) 48 and 909

D) 24 and 303

E) 24 and 909

QUESTION 2:

Which is a valid recursive definition of n!!?

A) (n)(n-2)(n-4)(n-6)(n-8)…(n-(n-2))

B) n*(n-2)!!

C) n when n is less than 3, n*(n-2)!! otherwise

D) none of the above

### SOLUTION:

Q1-48 and 945 Q2-n when n is less than 3, n*(n-2)!! Otherwise