What is a non recursive solution for Fibonacci-like sequence in Java?

Question

Given this pseudo code of a function

f(0) = 1; 
f(1) = 3; 
f(n) = 3 * f(n - 1) - f(n - 2); // for n >= 2.

Is there a non recursive way o

Answer 1

Here is simply a function with minimum line of code and maximum flexibility.

You can add any "initial values" and any other recursive "function" you want simply.

def fib(n):
  fibs = [1, 3]       # <--  your initial values here 
  if n == 1:
    return fibs[0]
  if n == 2:
    return fibs[:1]
  for i in range(2, n):
    fibs.append(3*fibs[-1] - fibs[-2])  # <-- your function here
  return fibs

And the result is:

n=10
print(fib(n))

[1, 3, 8, 21, 55, 144, 377, 987, 2584, 6765]