Leetcode_520 Detect Capital

        本人比较喜欢520这个数字（毕竟我深深的爱着我的女朋友），但加上这道题比较简单（属于easy等级），本人又是学渣一枚，又感觉好久没有写过博文了，随便写一篇滥竽充数吧[破涕为笑]。

        原题链接：https://leetcode.com/problems/detect-capital/?tab=Description

原题题目：

Given a word, you need to judge whether the usage of capitals in it is right or not.

We define the usage of capitals in a word to be right when one of the following cases holds:

1. All letters in this word are capitals, like "USA".
2. All letters in this word are not capitals, like "leetcode".
3. Only the first letter in this word is capital if it has more than one letter, like "Google".

Otherwise, we define that this word doesn't use capitals in a right way.

Example 1:

Input: "USA"Output: True

Example 2:

Input: "FlaG"Output: False

        首先，如果想要降低运行时间，降低时间复杂度非常必要，所以第一考虑不要使用双重甚至多重循环，这道题很特殊，就只有三种情况，将这三种情况都考虑进去，问题就迎刃而解了。

        最终的运行结果如图：