Number of calls for nth Fibonacci number

Question

Consider the following code snippet:

int fib(int N)
{
   if(N<2) return 1;
   return (fib(N-1) + fib(N-2));
}

Given that fib

Answer 1

This is a classic problem for solving with Recurrence Relations.

Specifically, the fibonacci problem has the following parameters:

f(0) = 1
f(1) = 1
f(n) = f(n-1) + f(n-2)

Once you master solving recurrences, you'll have no problem reaching the solution (which, incidently, is exactly the same as fib(n)).