LeetCode.520 Detect Capital

最新推荐文章于 2021-01-27 20:38:49 发布

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本文介绍了一种用于检查单词中大写字母使用是否正确的算法。该算法能够判断一个单词是否完全由大写字母组成、完全由小写字母组成或者仅有第一个字母为大写的情况，并据此确定单词的大写规则是否正确。

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题目：

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.

分析：

class Solution {
    public boolean detectCapitalUse(String word) {
        //判断给定的字符串是否是满足大写规则（即：1.全部为大写 2.全部为小写 3.只有首字母大写）
        //思路：判断大写字母个数和字符串长度的，如果不相等，（一个的情况只需要判断首字母，否则false）
        if(word.length()==0||word==null) return false;
        
        int countAlpha=0;
        for(char c:word.toCharArray()){
            if(c>=65&& c<=90){
                countAlpha++;
            }
        }
        
        if(countAlpha!=word.length()&&countAlpha!=0){
            if(!(countAlpha==1&&(word.charAt(0)>=65&&word.charAt(0)<=90))){
                return false;
            }
        }
        return true;
    }
}