proverkamerge/прюфер/Program.cs

class Programm
{
    static int[,] pruff;
    class pruf
    {
        static void Main()
        {
            int k = 0;
            using(StreamReader reader = new StreamReader("pruf.txt"))
            {
                string massiv = reader.ReadLine();
                while(massiv != null)
                {
                    k++;
                    massiv = reader.ReadLine();
                }
                pruff = new int[k, 2];
            }
            using (StreamReader reader = new StreamReader("pruf.txt"))
            {
                string massiv = reader.ReadLine();
                int l = 0;
                while (massiv != null)
                {
                    string[] rebra = new string[2];
                    rebra = massiv.Split(' ').ToArray();
                    pruff[l, 0] = Convert.ToInt32(rebra[0]);
                    pruff[l, 1] = Convert.ToInt32(rebra[1]);
                    l++;
                    massiv = reader.ReadLine();
                }
            }
            pruferr(pruff, k);
        }
        static void pruferr(int[,] prufer, int k)
        {
            string kod = " ";
            int a = 0;
            while (a != k - 1)
            {
                int flag = 0;
                int min = int.MaxValue;
                int stroka = 0;
                for (int i = 0; i < prufer.GetLength(0); i++)
                {
                    flag = 0;
                    for (int j = 1; j < 2; j++)
                    {
                        if (prufer[i,j] < min && prufer[i,j] != 0 && flag == 0)
                        {
                            min = prufer[i,j];
                            stroka = i;

                            for(int x = 0; x< prufer.GetLength(0); x++)
                            {
                                for(int y = 0; y < 1; y++)
                                {
                                    if(min == prufer[x,y])
                                    {
                                        min = int.MaxValue;
                                        flag = 1;
                                    }                                    
                                }
                            }
                        }
                    }
                    if (i == prufer.GetLength(0) - 1)
                    {
                        if (flag == 0)
                        {
                        min = prufer[stroka, 0];
                            if (a == k - 2)
                            {
                                kod = kod + min;
                            }
                            else
                            {
                                kod = kod + min + " ";
                            }
                        prufer[stroka, 0] = 0;
                        prufer[stroka, 1] = 0;
                        a++;
                         }
                    }
                }
            }
            Console.WriteLine(kod);
        }
    }
}