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.

思路：从尾巴开始扫，扫到第一个不是空格的字母停止。再继续扫，更新长度，扫到空格结束。

public class Solution {    public int lengthOfLastWord(String s) {    int index=s.length()-1;    int count=0;    while(index>=0&&s.charAt(index)==' ')    {        index--;    }    while(index>=0&&s.charAt(index)!=' ')    {    index--;    count++;    }    return count;}}

投机取巧做法：

public class Solution {    public int lengthOfLastWord(String s) {    String[] res=s.trim().split(" ");    return res[res.length-1].length();}}