leetcode: Climbing Stairs

问题描述：

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?

原问题链接：https://leetcode.com/problems/climbing-stairs/

问题分析

　　这个问题在之前的文章里有讨论过。它本质上就是一个fibonacci数列的问题。我们可以用一个简单的循环递推去求这个结果。关于它的解法在这里就不详述了。详细的代码实现如下：

public class Solution {
    public int climbStairs(int n) {
        if(n <= 1) return 1;
        int a = 1, b = 1, c = 0;
        for(int i = 2; i <= n; i++) {
            c = a + b;
            a = b;
            b = c;
        }
        return c;
    }
}