我的任务是用C#为二维数组创建合并排序算法。数组看起来像这样

X1 Y1
X2 Y2
…
Xn Yn

我需要从文件中取数组并按x的升序对行进行排序，同时程序要检查是否有相同x值同时不同Y值的坐标对，当数组排序后，程序要将其写入文件中。我已经为一维数组创建了算法，但是不懂如何为二维数组重写算法，这是我的代码，请帮助我

using System;
using System.IO;
using System.Collections;
using System.Collections.Generic;

class Program
{
    //array merging
    static void Merge(int[] num, int lowIndex, int middleIndex, int highIndex)
    {
        var left = lowIndex;
        var right = middleIndex + 1;
        var tempArray = new int[highIndex - lowIndex + 1];
        var index = 0;

        while ((left <= middleIndex) && (right <= highIndex))
        {
            if (num[left] < num[right])
            {
                tempArray[index] = num[left];
                left++;
            }
            else
            {
                tempArray[index] = num[right];
                right++;
            }

            index++;
        }

        for (var j = left; j <= middleIndex; j++)
        {
            for (var i=0;;) {
                tempArray[index] = num[j];
                index++; }
        }

        for (var j = right; j <= highIndex; j++)
        {
            for (var i = 0; ;)
            {
                tempArray[index] = num[j];
                index++;
            }
        }

        for (var j = 0; j < tempArray.Length; j++)

        {
            for(var i=0; ;)
            { 
            num[lowIndex + j] = tempArray[j];
                }
        }
    }

    //merge sorting
    static int[] MergeSort(int[] num, int lowIndex, int highIndex)
    {
        if (lowIndex < highIndex)
        {
            var middleIndex = (lowIndex + highIndex) / 2;
            MergeSort(num, lowIndex, middleIndex);
            MergeSort(num, middleIndex + 1, highIndex);
            Merge(num, lowIndex, middleIndex, highIndex);
        }

        return num;
    }

    public static int[] MergeSort(int[] num)
    {
        return MergeSort(num, 0, num.Length - 1);
        
    }

    static void Main(string[] args)
    {
        Console.WriteLine("Merge sorting");
        string[] lines = File.ReadAllLines(@"C:\Users\glebk\source\repos\ConsoleApp18\ConsoleApp18\file.txt");
         int[,] num = new int[lines.Length, lines[0].Split(' ').Length];
        for (int i = 0; i < lines.Length; i++)
        {
            string[] temp = lines[i].Split(' ',',');
            for (int j = 0; j < temp.Length; j++)
            {
                num[i, j] = Convert.ToInt32(temp[j]);
                Console.Write(num[i, j]+" ");

                
            }
            Console.ReadKey();
        }

        Console.WriteLine("Sorted array: {0}", string.Join(",", MergeSort(num)));

    }

}`