leetcode 58: Length of Last Word

class Solution {public:    int lengthOfLastWord(string s) {        if(s.empty())            return 0;        int res=0;        while(s[s.size()-1]==' ')            s.pop_back();        for(int i=s.size()-1;i>=0;i--)        {            if(s[i]!=' ')                res++;            else                break;        }        return res;    }};