青蛙跳台阶玩耍

public class Qwt {
    public static void main(String[] args) {

        int result = JumpFloor(4);
        System.out.println(result);
    }

    public static int JumpFloor(int target){

        if (target == 1){
            return 1;
        }else if (target == 2){
            return 2;
        }else if (target > 2){
            int a = 1;
            int b = 2;
            int result = 0;
            for (int i = 0; i < target - 2; i++) {
                result = a + b;
                a = b;
                b = result;
            }
            return result;
        }else {
            return Integer.parseInt(null);
        }
    }
}