58. Length of Last Word

https://leetcode.com/problems/length-of-last-word/description/
    int lengthOfLastWord(string s) {
        if(s.size() == 0) return 0;
        int i = s.size()-1;
        while(i>=0 && s[i] == ' ') i--;
        if(i == -1) return 0;
        int j;
        for(j=i; j>=0; j--) {
            if(s[j] == ' ') break;
        }
        return  i-j;
    }