public class FibonacciTest {
	public static void main(String[] args) {
		System.out.println("Fibonacci 1:   " + fibonacci(15));
		System.out.println("Fibonacci 2:   " + fibonacci2(15));
		System.out.println("Fibonacci 3:   " + fibonacci3(15));
	}


	public static int fibonacci(int  n) {
		if (n <= 1)
			return 1;
		return fibonacci(n-1) + fibonacci(n-2);
	}


	public static int fibonacci2(int  n) {
		int first = 1;
		int second = 1;
		int third = 1;
		for (int i=2; i<=n; i++) {
			third = first + second;	// compute new value
			first = second; 		// shift the others to the right
			second = third;
	 	}
		return third;
	}


	public static int fibonacci(int  n, int prev, int prevPrev) {
		if (n <= 0)
			return prev + prevPrev;
		else
			return fibonacci(n-1, prev + prevPrev, prev);

	}


	public static int fibonacci3(int  n) {
		if (n <= 1)
			return 1;
		return fibonacci(n-2, 1, 1);  // calls above method
	}

}