Forum Topics

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

namespace Shellbound
{
    class Program
    {
        static void Main(string[] args)
        {
            var topics = new Dictionary<string, List<string>>();
            List <string> input = Console.ReadLine().Split(new[] { ' ', ',', '-', '>' }, StringSplitOptions.RemoveEmptyEntries).ToList();

            while (input[0] != "filter")
            {
                if (topics.ContainsKey(input[0]) == false)
                {
                    topics[input[0]] = new List<string>();
                }

                for (int i = 1; i < input.Count; i++)
                {
                    if (topics[input[0]].Contains(input[i]) == false)
                    {
                        topics[input[0]].Add(input[i]);
                    }
                }

                input = Console.ReadLine().Split(new[] { ' ', ',', '-', '>' }, StringSplitOptions.RemoveEmptyEntries).ToList();
            }

            List<string> filterWords = Console.ReadLine().Split(',').ToList();

            foreach (var item in topics)
            {
                bool isValid = true;

                for (int i = 1; i < input.Count; i++)
                {
                    for (int j = i - 1; j < filterWords.Count; j++)
                    {
                        if (input[i] != filterWords[j])
                        {
                            isValid = false;
                        }
                    }
                }

                if (isValid == false)
                {
                    topics.Remove(item.Key);
                }
            }

            foreach (var item in topics)
            {
                List<string> result = item.Value.Select(x => "#" + x).ToList();
                Console.WriteLine($"{item.Key} | {string.Join(",", result)}");
            }
        }
    }
}