求出两个字符串中最大长度的相同的子字符串

   class Program
    {
        static void Main(string[] args)
        {
            string s1 = "abcdefghijklmn";
            string s2 = "abc";
            string s3 = "bcde";
            string s4 = "lmn";
            string s5 = "abdef";
            string s6 = "bcabcd";
            string s7 = "abcdghabcdef";
            string s8 = "events/eventinsight/insight";
            string s9 = "events";
            Console.WriteLine("s1:{0},s1:{1} {2} ", s1, s1, GetMaxSameString(s1, s1));
            Console.WriteLine("s1:{0},s2:{1} {2} ", s1, s2, GetMaxSameString(s1, s2));
            Console.WriteLine("s2:{0},s3:{1} {2} ", s2, s3, GetMaxSameString(s2, s3));
            Console.WriteLine("s3:{0},s4:{1} {2} ", s3, s4, GetMaxSameString(s3, s4));
            Console.WriteLine("s4:{0},s5:{1} {2} ", s4, s5, GetMaxSameString(s4, s5));
            Console.WriteLine("s1:{0},s6:{1} {2} ", s1, s6, GetMaxSameString(s1, s6));
            Console.WriteLine("s1:{0},s7:{1} {2} ", s1, s7, GetMaxSameString(s1, s7));
            Console.WriteLine("s8:{0},s9:{1} {2} ", s8, s9, GetMaxSameString(s8, s9));
            Console.ReadLine();
        }
        /// <summary>
        /// 得到某一字符在另一字符串中的index数组
        /// </summary>
        /// <param name="chr">某一字符</param>
        /// <param name="str">另一字符串</param>
        /// <returns>index数组</returns>
        static List<int> GetIndexArr(char chr, string str)
        {
            List<int> arr = new List<int>();
            for (int x = 0, len = str.Length; x < len; x++)
            {
                if (chr.Equals(str[x]))
                {
                    arr.Add(x);
                }
            }
            return arr;
        }

        /// <summary>
        /// 得到某一字符串数组中的最长字符
        /// </summary>
        /// <param name="list">某一字符串数组</param>
        /// <returns>最长字符</returns>
        static string GetMaxLenString(List<string> list)
        {
            string str = "";
            if (list.Count > 0)
            {
                str = list[0];
                for (int k = 0; k < list.Count; k++)
                {
                    if (list[k].Length > str.Length)
                    {
                        str = list[k];
                    }
                }
            }
            return str;
        }

        /// <summary>
        /// 得到最大相同长度字符串
        /// </summary>
        /// <param name="s1">字符串1</param>
        /// <param name="s2">字符串2</param>
        /// <returns>最大相同长度字符串</returns>
        static string GetMaxSameString(string s1, string s2)
        {
            List<string> list = new List<string>();
            int l1, l2;
            string maxStr,minStr;
            if (s1.Length > s2.Length)
            {
                l1 = s1.Length;
                l2 = s2.Length;
                minStr = s2;
                maxStr = s1;
            }
            else
            {
                l1 = s2.Length;
                l2 = s1.Length;
                minStr = s1;
                maxStr = s2;
            }

            for (int i = 0; i < l1; i++)
            {
                int j = 0;
                string sb = "";
                char chr = maxStr[i];
                List<int> arr = GetIndexArr(chr, s2);
                for (int y = 0; y < arr.Count; y++)
                {
                    j = arr[y];
                    int k = i;
                    while (k < l1 && j < l2)
                    {
                        if (maxStr[k] == minStr[j])
                        {
                            sb += minStr[j];
                            k++;
                        }
                        j++;
                    }
                    if (sb.Length > 0)
                    {
                        list.Add(sb);
                        sb = "";
                    }
                }
            }
            return GetMaxLenString(list);
        }
    }