Leetcode 520. Detect Capital 发现大写词 (字符串)

Input: "USA"
Output: True

Input: "FlaG"
Output: False

class Solution {
public:
    bool detectCapitalUse(string word) {
        if (word.length() == 0) {
            return true;
        }
        bool capitalFirst = false;
        int capitalCnt = 0;
        if (isupper(word[0])) {
            capitalFirst = true;
            capitalCnt++;
        }
        for (int i = 1; i < word.length(); i++) {
            if (isupper(word.at(i))) {
                capitalCnt++;
            }
        }
        if (capitalCnt == 0 ||
            capitalCnt == word.length() ||
            (capitalFirst && capitalCnt == 1)) {
            return true;
        }
        return false;
    }
};