// CS 101  Class Example: fibonacci functions

    // Classic definition of Fibonacci function
        
    public static int fibonacci(int n) {
        if (n < 2) {
            return n;
        } else {
            return fibonacci(n-1) + fibonacci(n-2);
        }
    }

    // Tail recursive Fibonacci (wrapper function)

    public static int fibIter(int n) {
        return fibTail(n, 1, 0, 1);
    }

    // Tail recursive helper function

    public static int fibTail(int n, int i, int FibIMinus1, int FibI) {
        if (i == n) {
            return FibI;
        } else {
            return fibTail(n, i+1, FibI, FibIMinus1 + FibI);
        }
    }

    // While loop version of Fibonacci function

    public static int fibWhile(int n) {
        int i = 1;
        int fibIMinus1 = 0;
        int fibI = 1;

        while (i < n) {
            i ++;
            int temp = fibIMinus1;
            fibIMinus1 = fibI;
            fibI = temp + fibI;
        }
        return fibI;
    }