#include <iostream>
using namespace std;

unsigned int iFib(unsigned int n);	// iterative
unsigned int rFib(unsigned int n);	// recursive

int main()
{
   unsigned int index;

   cout << "Which fibonnaci number would you like: ";
   cin >> index;

   cout << "Computing Fib(" << index << ") iteratively... " << endl;
   cout << "iFib(" << index << ") = " << iFib(index) << endl;
   cout << "Computing Fib(" << index << ") recursively... " << endl;
   cout << "rFib(" << index << ") = " << rFib(index) << endl;
}

unsigned int rFib(unsigned int n)
// recursive version
{
  if (n <= 0)         return 0;       // base case
  else if (n == 1)    return 1;       // base case
  else                 
      return rFib(n-1) + rFib(n-2);     // recursive computation
}   

unsigned int iFib(unsigned int n)
// iterative version
{
   unsigned int n1 = 1, n2 = 1, n3;
   unsigned int i = 2;
   while (i < n)
   {                   
      n3 = n1 + n2;
      n1 = n2;
      n2 = n3;
      i++;
   }
   return n2;
}