*LeetCode--Detect Capital

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.

自己的方法，一个一个字符的判断（要注意边界条件）

class Solution {
    public boolean detectCapitalUse(String word) {
        if(word == null || word.length() == 0) return false;
        if(word.length() == 1) return true;
        boolean flag = (word.charAt(0) >= 'A' && word.charAt(0) <= 'Z') ? true : false;
        
        if(flag){
            boolean upper = (word.charAt(1) >= 'A' && word.charAt(1) <= 'Z' && flag) ? true : false;
            for(int i = 1; i < word.length(); i++){
                if(upper && word.charAt(i) >= 'a' && word.charAt(i) <= 'z') return false;
                if(!upper && word.charAt(i) >= 'A' && word.charAt(i) <= 'Z') return false;
            }
        }else{
            for(int i = 1; i < word.length(); i++){
                if(word.charAt(i) >= 'A' && word.charAt(i) <= 'Z') return false;
            }
        }
        return true;
    }
}

　　

如 mL, FFFFFFFFFFFFf

别人的方法：直接调用线程的方法

public boolean detectCapitalUse(String word) {
        return word.equals(word.toUpperCase()) || 
               word.equals(word.toLowerCase()) ||
               Character.isUpperCase(word.charAt(0)) && 
               word.substring(1).equals(word.substring(1).toLowerCase());
    }
A slightly more verbose, but more efficient solution:

    public boolean detectCapitalUse(String word) {
        int numUpper = 0;
        for (int i=0;i<word.length();i++)
            if (Character.isUpperCase(word.charAt(i))) numUpper++;
        if (numUpper == 1) return Character.isUpperCase(word.charAt(0));
        return numUpper == 0 || numUpper == word.length();
    }