151.Reverse Words in a String

class Solution {
public:
    /**
     * @param s : A string
     * @return : A string
     */
    string reverseWords(string s) {
        istringstream is(s);
        is >> s;
        string t; 
        while (is >> t) {
            s = t + " " + s;
        }
        return (s[0] == ' ') ? "" : s;
    }
};