Najdłuższy wspólny podciąg

namespace Zad3
{
    class Program
    {

        static int[,] LongestCommonSubsequence(string s1, string s2)
        {
            int[,] common = new int[s1.Length + 1, s1.Length + 1];
            for (int i = 1; i < s1.Length; i++)
            {
                for (int j = 1; j < s2.Length; j++)
                {
                    if (s1[i - 1] == s2[j - 1]) common[i, j] = common[i - 1, j - 1] + 1;
                    else common[i, j] = common[i - 1, j] > common[i, j - 1] ? common[i - 1, j] : common[i, j - 1];
                }
            }

            return common;
        }
        static string WriteLCS(int[,] c, string s1, string s2, int i, int j)
        {
            if (i == 0 || j == 0)
                return "";
            else if (s1[i - 1] == s2[j - 1])
                return WriteLCS(c, s1, s2, i - 1, j - 1) + s1[i - 1];
            else if (c[i, j - 1] > c[i - 1, j])
                return WriteLCS(c, s1, s2, i, j - 1);
            else
                return WriteLCS(c, s1, s2, i - 1, j);
        }
        static void Main(string[] args)
        {
            string s1 = "ABCBDAB";
            string s2 = "BDCABA";
            int[,] c = LongestCommonSubsequence(s1, s2);
            Console.WriteLine(WriteLCS(c,s1,s2,s1.Length,s2.Length));


            Console.ReadKey();
        }
    }
}