private static List<List<string>> PalindromePartitioning(string str)
        {
            var list = new List<List<string>>();

            if (str == string.Empty) return list;

            Backtrack(list, new List<string>(), new List<string>() { str });

            return list;
        }

        private static void Backtrack(List<List<string>> list, List<string> temp, List<string> strs)
        {
            var next = new List<string>();

            next.Print();

            for (int i = 0; i < strs.Count; i++)
            {
                if (IsPalindrome(strs[i]))
                {
                    temp.Add(strs[i]);
                }

                int low = 0;
                int high = strs[i].Length - 1;
                int mid = low + (high - low) / 2;

                if (high < low) break;

                next.Add(strs[i].Substring(low, mid+1));
                if (mid + 1 <= high) next.Add(strs[i].Substring(mid + 1, high-mid));
            }

            if (temp.Count != 0) list.Add(temp);

            Backtrack(list, new List<string>(), next);
        }

        private static bool IsPalindrome(string str)
        {
            int low = 0;
            int high = str.Length - 1;

            while (high > low)
            {
                char front = str[low];
                char back = str[high];

                if (front != back) return false;

                low++;
                high--;
            }

            return true;
        }