520 Detect Capital

我的code，就是阅读理解，但是比较完备，tolerant String可能不规范的情况。

	public boolean detectCapitalUse(String word) {
		if (word == null || word.length() <= 1) {
			return true;
		}
		for (int i = 0; i < word.length(); i++) {
			//首字母小写
			if (isLowerCaseLetter(word.charAt(0))) {
				if (!isLowerCaseLetter(word.charAt(i))) {
					return false;
				}
			}
			//首字母大写
			else if (isUpperCaseLetter(word.charAt(0))) {
				if (isUpperCaseLetter(word.charAt(1))) {
					if (i > 1 && !isUpperCaseLetter(word.charAt(i))) {
						return false;
					}
				} else if (isLowerCaseLetter(word.charAt(1))) {
					if (i > 1 && !isLowerCaseLetter(word.charAt(i))) {
						return false;
					}
				}
			} else {
				return false;
			}
		}
		return true;
	}

	private boolean isLowerCaseLetter(char c) {
		return c <= 'z' && c >= 'a';
	}

	private boolean isUpperCaseLetter(char c) {
		return c <= 'Z' && c >= 'A';
	}

简洁的代码：

public class Solution {
    public boolean detectCapitalUse(String word) {
        int cnt = 0;
        for(char c: word.toCharArray()) if('Z' - c >= 0) cnt++;
        return ((cnt==0 || cnt==word.length()) || (cnt==1 && 'Z' - word.charAt(0)>=0));
    }
}