LeetCode: 520 Detect Capital(easy)-优快云博客

本文链接：https://blog.youkuaiyun.com/lxin_liu/article/details/85000794

本文介绍了一种检测单词中大写字母使用是否正确的算法。该算法通过三种情况判断：所有字母大写，如USA；所有字母小写，如leetcode；仅首字母大写，如Google。提供了两种实现方案，一种通过逐个检查字母，另一种通过计数大写字母总数进行判断。

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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.

代码：

自己的：

class Solution {
public:
    bool detectCapitalUse(string word) {
        bool result = 1;
        if (word[0] < 'a'){
            if (word[1] < 'a'){
                for(int i = 2; i < word.size(); i++){
                    if(word[i] > 'Z'){
                        result = 0;
                        break;
                    }
                }
            }
            else{
                for(int i = 2; i < word.size(); i++){
                    if(word[i] < 'a'){
                        result = 0;
                        break;
                    }
                }
            }
        }
        else{
            for(auto c : word){
                if (c < 'a'){
                    result = 0;
                    break;
                }
            }
        }
        return result;  
    }
};

别人的：

class Solution {
public:
    bool detectCapitalUse(string word) {
        int cnt = 0;
        for(int a = 0; a < word.length(); a++ ) {
            if('Z' - word[a] >= 0) 
                cnt++;
        }
        if(cnt == word.length() || cnt == 0 || (cnt == 1 && ('Z' - word[0] >= 0)))
            return true;
        return false;
        
    }
};

对大写字母计数，然后再判断（全是大写、全是小写、首字母大写）