public static void test(int num) {
  if (num <= 2) return 1;
  else return (test(num-1) + test(num-2));
}

------解决方案--------------------
Java code

public class Main {

    public static void main(String[] args) {
        System.out.println(getN(30));
    }
    // 这叫斐波那契数列
    public static int getN(int n) {
        if (n == 1 || n == 2)
            return 1;
        else
            return getN(n - 1) + getN(n - 2);
    }

}