类斐波那契数列的java实现

递归实现

    // f(n)=f(n-1)+3f(n-2);f(0)=0;f(1)=1; n>=2
    public static int fac(int k) {

        if (k == 0) {
            return 0;

        }
        if (k == 1) {
            return 1;
        }

        return fac(k - 1) + 3 * fac(k - 2);

    }

循环实现

    public static void main(String[] args) {

        // f(n)=f(n-1)+3f(n-2);f(0)=0;f(1)=1;
        int a = 0, b = 1, c = 0;

        for (int i = 2; i <= 11; i++) {

            c = b + 3 * a;
            a = b;
            b = c;

        }
        System.out.println(c);

    }