/*
    Which is your favorite Fibonacci function?
*/

#include<stdio.h>
#include<stdlib.h>

int fib1(int n)
{
  if (n<3) return 1; else return fib1(n-1) + fib1(n-2);
}



int fib2(int n)
{
  int fibiter(int n, int a, int b) {
    if (n<3) return b; else return fibiter(n-1,b,a+b);
  }
  return fibiter(n,1,1);
}



int fib3(int n)
{
  int a = 1, b = 1;
  int temp;
  while (n>2)
    { temp = b;  b = a+b;  a = temp;  n--; }
  return b;
}

// Which two versions have more in common?


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));
  printf("without recursion it's still %d\n", fib3(n));
  return(0);
}