Leetcode: Length of Last Word

Problem:

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.

Solution:  This problem is easy, traverse from the end of the string and do not forget to delete the trailing spaces.

code:

public class Solution {
    public int lengthOfLastWord(String s) {
        if (s == null || s.length() ==0) {
            return 0;
        }
        
        int start = 0;
        int end = s.length() - 1;
        while (start <= end && s.charAt(end) == ' ') {
                end--;
        }
        int count = 0;
        while (start <= end && s.charAt(end) != ' ') {
            count++;
            end--;
        }
        return count;
    }
}