public String reverseWords(String s) {
        String[]  list = s.split(" ");
        String result = "";
        for(int i = list.length-1 ;i >= 0 ;i--){
            if(!list[i].equals("") )
                result = result+ list[i]+" ";
        }
        if(result.length() > 0)
            return result.substring(0,result.length()-1);
        else
            return result;
    }