leetcode 58:Length of Last Word

题目：

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：

额，这题比较简单，从最后一个元素开始往前扫描就行啦，刚开始跳过空格。

实现：
class Solution {
public:
int lengthOfLastWord(string s) {
int size = s.size();
int i = size-1;
while (i >= 0 && s[i] == ' ') --i;
if (i < 0) return 0;
int j = i;
for (; j >= 0 && s[j] != ' '; --j){}
return (i-j);
}
};