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.

思路：字符串由前后空格分隔

java：

1. public int lengthOfLastWord(String s) {
2. int slen = s.length();
3. int index = slen-1;
4. while(index>=0 && s.charAt(index)==' ') index--;
5. if(index<0) return 0;
6. int end = index+1;
7. while(index>=0 && s.charAt(index)!=' ') index--;
8. int start = index+1;
9. return end - start;
10. }