/// <summary>

    /// 优化的算法

    /// </summary>

    public class BadWordsFilter2

    {

        private HashSet<string> hash = new HashSet<string>();



        private ushort[] fastCheck = new ushort[char.MaxValue + 1];

        private ushort[] startLength = new ushort[char.MaxValue + 1];

        private ushort[] endLength = new ushort[char.MaxValue + 1];



        private int maxWordLength = 0;

        private int minWordLength = int.MaxValue;



        public void AddKey(string word)

        {

            if (word.Length > 16)

            {

                throw new Exception("参数最大16个字符");

            }



            maxWordLength = Math.Max(maxWordLength, word.Length);

            minWordLength = Math.Min(minWordLength, word.Length);

            //字符出现的位置(1-16),

            for (int i = 0; i < word.Length; i++)

            {

                fastCheck[word[i]] |= (byte)(1 << i);

            }



            ushort mask = (ushort)(1 << word.Length - 1);

            //以x开始的字符的长度

            startLength[word[0]] |= mask;

            //以x结束的字符的长度

            endLength[word[word.Length - 1]] |= mask;



            hash.Add(word);

        }



        public bool HasBadWord(string text)

        {

            for (int index = 0; index < text.Length; index++)

            {

                int count = 0;

                int maxIndex = Math.Min(maxWordLength + index, text.Length);

                char begin = text[index];

                for (int j = index; j < maxIndex; j++)

                {

                    char current = text[j];

                    ushort mask = (ushort)(1 << count);

                    if ((fastCheck[current] & mask) == 0)

                    {

                        index += count;

                        break;

                    }

                    ++count;

                    if ((startLength[begin] & mask) > 0 && (endLength[current] & mask) > 0)

                    {

                        string sub = text.Substring(index, count);

                        if (hash.Contains(sub))

                        {

                            //index += (count - 1);

                            return true;

                        }

                    }

                }

            }

            return false;

        }

        public string FindOne(string text)

        {

            for (int index = 0; index < text.Length; index++)

            {

                int count = 0;

                int maxIndex = Math.Min(maxWordLength + index, text.Length);

                char begin = text[index];

                for (int j = index; j < maxIndex; j++)

                {

                    char current = text[j];

                    ushort mask = (ushort)(1 << count);

                    if ((fastCheck[current] & mask) == 0)

                    {

                        index += count;

                        break;

                    }

                    ++count;

                    if ((startLength[begin] & mask) > 0 && (endLength[current] & mask) > 0)

                    {

                        string sub = text.Substring(index, count);

                        if (hash.Contains(sub))

                        {

                            index += (count - 1);

                            return sub;

                        }

                    }

                }

            }

            return string.Empty;

        }



        public IEnumerable<string> FindAll(string text)

        {

            for (int index = 0; index < text.Length; index++)

            {

                int count = 0;

                int maxIndex = Math.Min(maxWordLength + index, text.Length);

                char begin = text[index];

                for (int j = index; j < maxIndex; j++)

                {

                    char current = text[j];

                    ushort mask = (ushort)(1 << count);

                    if ((fastCheck[current] & mask) == 0)

                    {

                        index += count;

                        break;

                    }

                    ++count;

                    if ((startLength[begin] & mask) > 0 && (endLength[current] & mask) > 0)

                    {

                        string sub = text.Substring(index, count);

                        if (hash.Contains(sub))

                        {

                            index += (count - 1);

                            yield return sub;

                            break;

                        }

                    }

                }

            }

        }

    }