leetcode -- Length of Last Word

Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string.

If the last word does not exist, return 0.

Note: A word is defined as a character sequence consists of non-space characters only.

For example, 
Given s = "Hello World",
return 5.

[解题思路]

从最后往前扫描。处理如下三种模式：(*表示若干个空格)
1. "*"
2. "*word"
3. "*word*"
4. "word*"

public int lengthOfLastWord(String s) {
        // Start typing your Java solution below
        // DO NOT write main() function
        if(s.length() == 0)
            return 0;
        
        String[] strs = s.split(" ");
        for(int i = strs.length - 1; i >= 0; i++){
            if(isWord(strs[i])){
                return strs[i].length();
            }
        }
        return 0;
    }
    
    public boolean isWord(String s){
        if(s.length() == 0)
            return false;
            
        for(int i = 0; i < s.length(); i++){
            if((s.charAt(i) < 'a' && s.charAt(i) > 'z') ||
                (s.charAt(i) < 'A' && s.charAt(i) > 'Z')){
                    return false;
                }
        }
        
        return true;
    }
}