public bool AddReverse(Difference difference, int startIndex) { if (startIndex == difference.Length) { if (EndOfWord) { return(false); } EndOfWord = true; return(true); } DifferenceNode child; char c = difference.CharAtFromEnd(startIndex); if (!Children.TryGetValue(c, out child)) { child = new DifferenceNode(); Children.Add(c, child); } var result = child.Add(difference, startIndex + 1); return(result); }