using System;

public class Program

{

    public static void Main()

    {

        Int32 nM = 10, 

            nN = 20;

        Random oR = new Random();

        Int32[][] aArr = new Int32[nN][];

        for (Int32 nI = 0; nI < nN; nI++) {

            aArr[nI] = new Int32[nM];

            for (Int32 nJ = 0; nJ < nM; nJ++) {

                if (nI % 2 == 0) {

                    aArr[nI][nJ] = nI * nM + nJ;

                } else {

                    aArr[nI][nJ] = (nI + 1) * nM - nJ - 1;

                }

            }

        }

        for (Int32 nI = 0; nI < nN; nI++) {

            showArray(aArr[nI]);

        }

        Console.WriteLine("Result of 2D array");

    }

    private static void showArray(Int32[] aArr){

        String[] aS = new String[aArr.Length];

        for (Int32 nI = 0; nI < aArr.Length; nI++) {

            aS[nI] = String.Format("{0,-3}", aArr[nI]);

        }

        Console.WriteLine(String.Join(" ", aS));

    }

}