Detect Capital–LeetCode#520

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.
翻译:给定一个字符串,判断是否为capitals,三类单词可以被判定为capitals单词,
例如:”USA”:全为大写字母;”leetcode”:全为小写字母;”Google”:首字母为大写字母,其余全为小写字母;
其余全不符合要求.提示:给出的都为非空且由大小写字母组成的字符串。
思路:通过查询ASCII表,大写字母范围:65-90,小写字母范围:97-122。遍历每个字母得到大写字母和小写字母的数量,其中一个数量为1,都为true;若大写字母数量为1,且第一个字符为大写字母,返回true。

public class DetectCapital {
    public boolean detectCapitalUse(String word) {
        Boolean result = true;
        int bCount = 0;
        int sCount = 0;
        for (int i=0;i<word.length();i++){
            if (word.charAt(i) > 64 && word.charAt(i) < 91){
                bCount++;
            }else if (word.charAt(i)>96 && word.charAt(i)<123){
                sCount++;
            }
            if (bCount == 0 || sCount == 0){
                result = true;
            }else if (bCount == 1 && word.charAt(0)>64 && word.charAt(0)<91){
                result = true;
            }else {
                result = false;
            }
        }
        return result;
    }
    public static void main(String[] args) {
        DetectCapital detectCapital = new DetectCapital();
        System.out.println(detectCapital.detectCapitalUse("GOOGLE"));
    }
}

显然,这肯定不是最优的解决方法,
public boolean detectCapitalUse(String word) {
         return word.matches("[A-Z]+|[a-z]+|[A-Z][a-z]+");
}
这种方法是通过matches方法,通过正则表达式匹配正确的字符串 [A-Z]+ 或 [a-z]+ 或 [A-Z][a-z]+

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