leetcode 520. Detect Capital

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.

解法1:

class Solution(object):
    def detectCapitalUse(self, word):
        """
        :type word: str
        :rtype: bool
        """
        """
        USA=True
        CN=True
        C=False?
        U=False?
        ""=?
        usa=True
        Usa=True
        uSa=False
        """
        # get first letter:
        # if first letter is Uppaer case: check all the following letter is Lower case or upper case
        # if first letter is lower case: check all the following letter is lower case
        # otherwise, False
        if word[0].islower(): return all(c.islower() for c in word[1:])
        else: return all(c.isupper() for c in word[1:]) or all(c.islower() for c in word[1:])        

换一种思维：大写字母个数==0或者==1个(仅为首字母)或者字符串长度！

class Solution(object):
    def detectCapitalUse(self, word):
        """
        :type word: str
        :rtype: bool        
        """
        upper_cnt = 0
        for c in word:
            if c.isupper(): upper_cnt += 1
        return upper_cnt == 0 or (upper_cnt == 1 and word[0].isupper()) or upper_cnt == len(word)