Climbing Stairs

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?


Note: Given n will be a positive integer.


代码如下：

public class Solution {    public int climbStairs(int n) {        int a=1;        int b=1;        while(n--){            a = (b += a) - a;        }        return a;    }}