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.

Solution:

One pointer points to the end of string, then loop from right to left.

Run time complexity is O(n), constant space.

public class Solution {
    public int lengthOfLastWord(String s) {
        if(s == null || s.length() == 0)
            return 0;
        
        s = s.trim();  //get rid of space at beginning and end
        int count = 0;
        for(int i = s.length() - 1; i >= 0; i--) {
            if(s.charAt(i) != ' ') {
                count++;
            }else {
                return count;
            }
        }
        return count;
    }
}