在你面前有一个n阶的楼梯，你一步只能上1阶或2阶

public class TestFloor {

	public static void main(String[] args) {
		System.out.println("当N=11时："+ladder(11) +" "+"当N=9时："+ ladder(9));
	}

	private static int ladder(int n) {
		// TODO Auto-generated method stub
		if(n==1) {
			return 1;
		}else if(n==2) {
			return 2;
		}else {
			return ladder(n-1) + ladder(n-2);
		}
	}
}