class Solution {

public:

    string reverseWords(string s) {

        string ans = "", t = "";

        istringstream is(s);//

        while(is >> t)

        {

            reverse(t.begin(), t.end());

            ans += t + " ";//err.

        }

        ans.pop_back();

        return ans;

    }

};

class Solution {

public:

    string reverseWords(string s) {

        int start = , end = ;

        while(start<s.size() && end<s.size())

        {

            while(end < s.size() && s[end]!=' ') end++;

            for(int i=start, j=end-; i<j; i++, j--)//

            {

                swap(s[i], s[j]);//

            }

            start = ++end;

            //start = end + 1;

            //end++;

        }

        return s;

    }

};