2017算法课.07(Detect Capital)

520. Detect Capital

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Description Submissions Solutions

• Total Accepted: 16777
• Total Submissions: 31953
• Difficulty: Easy
• Contributors: love_Fawn

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

Note: The input will be a non-empty word consisting of uppercase and lowercase latin letters.

这道题目的题号很有意思520。。。。。。。。。。。。。。。。。。。。

该题目给出了三种情况：

1.全部大写

2.全部小写

3.首字母大写

首先当只有一个字母的时候，无论是大写还是小写，都是正确的

其次，首字母大写的话，其后字母必须是小写或者必须是大写，利用循环解决

如果首字母小写，其后必须是小写，也是利用循环来实现的

代码如下：

class Solution {
public:
    bool detectCapitalUse(string word) {
        if (word.length() <= 1) return true;
        if (islower(word[0]) || (isupper(word[0]) && islower(word[1]))) {
            for (int i = 1; i < word.length(); i++)
                if (isupper(word[i])) return false;
        } else {
            for (int i = 1; i < word.length(); i++)
                if (islower(word[i])) return false;
        }
        return true;
    }
};