【Leetcode】【Easy】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?

解题：

简单的运算后，可知此题为斐波那契数列生成题。

解题步骤：

1、新建三个初始变量step1 = 1，step2 = 2，result；

2、注意算法从n = 3开始，所以当n < 3时，直接返回结果。

 1 class Solution {
 2 public:
 3     int climbStairs(int n) {
 4         int result = 0;
 5         int stepOne = 1;
 6         int stepTwo = 2;
 7         
 8         if (n == 1 || n == 2)
 9             return n;
10         
11         while (n-- && n >= 2) {
12             result = stepOne + stepTwo;
13             stepOne = stepTwo;
14             stepTwo = result;
15         }
16         
17         return result;
18     }
19 };

附录：

斐波那契以及其他有趣数学数列