/// <summary> /// Removes the current board hash from history. /// </summary> private void RemoveHistoryHash() { int hash = currentBoard.GetHashCode(); int freq = historyHashes[hash]; // if the frequency is more than 1 decrement it, otherwise remove the hash if (freq > 1) { historyHashes[hash] = freq - 1; } else { historyHashes.Remove(hash); } }