leetcode 520. Detect Capital

Description

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:

All letters in this word are capitals, like "USA".
All letters in this word are not capitals, like "leetcode".
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.

My Ugly solution

• 手写规则...

class Solution {
public:
    bool detectCapitalUse(string word) {
        if (word[0] < 97) {
            if (word[1] < 97) for (int i = 2; i < word.size(); ++i) if (word[i] >= 97) return false; else;
            else for (int i = 2; i < word.size(); ++i) if (word[i] < 97) return false; else;
        } else for (int i = 1; i < word.size(); ++i) if (word[i] < 97) return false; else;
        return true;
    }
};

Discuss

• pythonic

def detectCapitalUse(self, word):
    return word.isupper() or word.islower() or word.istitle()

• cnt记录大写, 判断大写次数以及出现位置

public class Solution {
    public boolean detectCapitalUse(String word) {
        int cnt = 0;
        for(char c: word.toCharArray()) if('Z' - c >= 0) cnt++;
        return ((cnt==0 || cnt==word.length()) || (cnt==1 && 'Z' - word.charAt(0)>=0));
    }
}

重新仿写如下:

class Solution {
public:
    bool detectCapitalUse(string word) {
        int cnt = 0;
        for (auto &w:word) cnt += ((w - 'Z') <= 0);
        return cnt == 0 || cnt == word.size() || (cnt == 1 && word[0] - 'Z' <= 0);
    }
};

Reference

• leetcode 520. Detect Capital