Leetcode-length of last word

Question:

Given a stringSConsists 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,
GivenS="Hello World",
Return5.

Ideas:

Start from the end

package string;public class LengthOfLastWord {    public int lengthOfLastWord(String s) {        int n = 0;        if (s == null || (n = s.length()) == 0) return 0;        int postSpaceIndex = -1;        for (int i = n - 1; i >= 0; --i) {            if (s.charAt(i) != ‘ ‘) {                postSpaceIndex = i;                break;            }        }                int count = 0;        for (int i = postSpaceIndex; i >= 0; --i) {            if (s.charAt(i) != ‘ ‘)                ++count;            else                break;        }                return count;    }        public static void main(String[] args) {        // TODO Auto-generated method stub        String s = "Hello world  ";        LengthOfLastWord l = new LengthOfLastWord();        System.out.println(l.lengthOfLastWord(s));    }}

 

Leetcode-length of last word