class Solution {
public:
    string reverseWords(string s) {
        int size = s.size();
        int i=0;
        int tmp = i;
        while(i<size)
        {
           if(s[i] == ' ')
           {
               int left = tmp;
               int right = i-1;
               while(left<right)
               {
                   swap(s[left],s[right]);
                   left++;
                   right--;
               }
               tmp = i+1;
           }
           i++;
        }
        int left = tmp;
        int right = size-1;
        while(left<right)
        {
            swap(s[left],s[right]);
            left++;
            right--;
        }
        return s;
    }
};