Merge Sort in C#

Welcome to the Merge Sort in C# page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

using System;
using System.Linq;
using System.Collections.Generic;

public class MergeSort
{
    public static List<int> Sort(List<int> xs) => Sort(xs.Select(x => new List<int>() {x}).ToList()).First();
    public static List<List<int>> Sort(List<List<int>> xs)
    {
        if (xs.Count <= 1)
            return xs;
        var x0 = xs[0];
        var x1 = xs[1];
        xs.RemoveAt(0);
        xs.RemoveAt(0);
        return Sort(new List<List<int>>()
        {
            Merge(x0, x1)
        }.Concat(Sort(xs).ToList()).ToList());
    }

    public static List<int> Merge(List<int> xs, List<int> ys)
    {
        if (!xs.Any())
            return ys;
        if (!ys.Any())
            return xs;
        if (xs[0] < ys[0])
        {
            var x0 = xs[0];
            xs.RemoveAt(0);
            return new List<int>() {x0}.Concat(Merge(xs, ys)).ToList();
        }
        var y0 = ys[0];
        ys.RemoveAt(0);
        return new List<int>() {y0}.Concat(Merge(xs, ys)).ToList();
    }

    public static void ErrorAndExit()
    {
        Console.WriteLine("Usage: please provide a list of at least two integers to sort in the format \"1, 2, 3, 4, 5\"");
        Environment.Exit(1);
    }

    public static void Main(string[] args)
    {
        if (args.Length != 1)
            ErrorAndExit();
        try
        {
            var xs = args[0].Split(',').Select(i => Int32.Parse(i.Trim())).ToList();
            if (xs.Count() <= 1)
                ErrorAndExit();
            var sortedXs = Sort(xs);
            Console.WriteLine(string.Join(", ", sortedXs));
        }
        catch
        {
            ErrorAndExit();
        }
    }
}

Merge Sort in C# was written by:

• Parker Johansen

If you see anything you'd like to change or update, please consider contributing.

Note: The solution shown above is the current solution in the Sample Programs repository as of Mar 26 2019 00:26:31. The solution was first committed on Dec 30 2018 01:16:19. As a result, documentation below may be outdated.

How to Implement the Solution

No 'How to Implement the Solution' section available. Please consider contributing.

How to Run the Solution

No 'How to Run the Solution' section available. Please consider contributing.