/*
    Which is your favorite Fibonacci function?
*/

#include<stdlib.h>


int fib1(int n)
{
  if (n<2) return 1; else return fib1(n-1) + fib1(n-2);
}



int fib2(int n, int a, int b)
{
  if (n<2) return b; else return fib2(n-1,b,a+b);
}
// this function is meant to be called with 1,1 for a and b.



int fib3(int n)
{
  int a = 1, b = 1;
  int temp;
  while (n>1)
    { temp = b;  b = a+b;  a = temp;  n--; }
  return b;
}




int main(int arc, char **argv)
{ 
  int n = atoi(argv[1]);  // use command line arg for value
  printf("the %dth Fibonacci number is %d\n", n,fib1(n));
  printf("with tail recursion it's also %d\n", fib2(n,1,1));
  printf("without recursion it's still %d\n", fib3(n));
  exit(0);
}