题目描述：
You are climbing a stair case. It takes n steps to reach to the top.
Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?
题目大意：
你正在爬楼梯。爬到顶部需要n步。
每一次你爬1步或者2步。爬到顶部有多少种不同的方式？ ...
You are climbing a stair case. It takes n steps to reach to the top.
Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?
你正在爬楼梯。爬到顶部需要n步。
每一次你爬1步或者2步。爬到顶部有多少种不同的方式？ ...