AlphabetCheckers.Checker.Divide C# (CSharp) Method

        public BaseChain Divide(BaseChain chain)
        {
            var firstChain = new ActualChain(chain);
            var stack = new Stack();
            stack.Push(firstChain);
            ArrayList list = alphabet.GetLengthList();
            do
            {
                var actChain = (ActualChain)stack.Pop();
                BaseChain chain4Check = actChain.Source;

                for (int i = list.Count - 1; i >= 0; i--)
                {
                    BaseChain word;
                    if (chain4Check.GetLength() >= (int)list[i])
                    {
                        var it = new IteratorStart(chain4Check, (int)list[i], 1);
                        it.Next();
                        word = (BaseChain)it.Current();
                    }
                    else
                    {
                        continue;
                    }

                    if (alphabet.Contains(word))
                    {
                        // solution is found
                        if (chain4Check.GetLength() == (int)list[i])
                        {
                            actChain.RemoveCharacter((int)list[i]);
                            return actChain.GetResult();
                        }

                        var newChain = (ActualChain)actChain.Clone();
                        newChain.RemoveCharacter((int)list[i]);
                        stack.Push(newChain);
                    }
                }
            }
            while (stack.Count > 0);
            return null;
        }