using System;

using System.Collections.Generic;

using System.Xml;

using System.Linq;

using System.Xml.Linq;

​

public class Program

{

    public enum CategoryType

    {

        Other,

        Easy,

        Intermediate,

        Hard

    }

    public class Item

    {

        public string Title { get; set; }

        public string Link { get; set; }

        public DateTime Date { get; set; }

        public CategoryType Category { get; set; }

    }

    public static void Main()

    {

        const string url = "https://www.reddit.com/r/dailyprogrammer/.rss";

        var xdoc = XDocument.Load(url);

        var items = from item in xdoc.Descendants("item")

            let title = item.Element("title").Value

            select new Item

            {

                Title = title,

                Link = item.Element("link").Value,

                Date = DateTime.Parse(item.Element("pubDate").Value),

                Category = ExtractCategory(title)

            };

​

        var sorted = items.OrderBy(x => x.Category);

        var array = Split(sorted);

        Print(array);

    }

    private static CategoryType ExtractCategory(string title)

    {

        var categories = new Dictionary<string, CategoryType>

        {

            { "[Easy]", CategoryType.Easy },

            { "[Intermediate]", CategoryType.Intermediate },

            { "[Hard]", CategoryType.Hard }

        };

        return categories.FirstOrDefault(x => title.Contains(x.Key)).Value; 

    }

    private static void Print(Item[,] array)

    {

        Console.WriteLine("Other | Easy | Intermediate | Hard ");

        Console.WriteLine("------|------|--------------|------");

        for (int i = 0; i < array.GetLength(0); i++)

        {

            for (int j = 0; j < array.GetLength(1); j++)

            {

                var item = array[i, j];

                Console.Write("| " + (item != null ?

                              string.Format("[{0}]({1})", item.Title, item.Link)

                              : "   "));

            }

            Console.WriteLine(" |");

        }

    }

    private static Item[,] Split(IEnumerable<Item> items)

    {

        var splitedItems = items.GroupBy(j => j.Category).ToArray();

        var array = new Item[splitedItems.Max(x => x.Count()), splitedItems.Length];

        for (var i = 0; i < splitedItems.Length; i++)

            for (var j = 0; j < splitedItems.ElementAt(i).Count(); j++)

                array[j, i] = splitedItems.ElementAt(i).ElementAt(j);

        return array;

    } 

}