A function f is defined by the rule that f(n) = n if 0≤n≤3 and f(n) = f(n - 1) + 2f(n - 2) + 3f(n - 3) if n> 3.
(a) Write a procedure that computes f by means of a recursive process.
(b) Write a procedure that computes f by means of an iterative process.