[LeetCode] 58. 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.

public class Solution {
    public int lengthOfLastWord(String s) {
        int len = s.length();
        if(0 == len)
            return 0;
            
        int l = 0;
        int r = 0;
        
        int retl = l;
        int retr = r;
        
        for(int i = 0; i < len; ++i){
            if(Character.isLetter(s.charAt(i))){
                r++;
            }else{
                if(l != r){
                    retl = l;
                    retr = r;
                }
                r++;
                l=r;
            }
        }
        
        // Error: You have to judge for the last time, if the sentence is ending with a word.
        if(l != r){
            retl = l;
            retr = r;
        }
        
        return retr-retl;
        
    }
}