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：

先将下标定位到最后一个非空格字符处，该处与前一处空格下标的差值即为最后单词的长度

解法：

 1 public class Solution 2 { 3     public int lengthOfLastWord(String s) 4     { 5         int i = s.length() - 1; 6         int length = 0; 7  8         while(i >= 0 && s.charAt(i) == ‘ ‘) 9             i--;10 11         while(i >= 0 && s.charAt(i) != ‘ ‘)12         {13             i--;14             length++;15         }16 17         return length;18     }19 }

LeetCode 58 Length of Last Word