QueryMess

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

namespace QueryMess
{
    public class QueryMess
    {
        public static void Main()
        {
            Regex validPair = new Regex(@"^(.*?=.*?)$");
            Regex spaces = new Regex(@"((\+|%20)(\+|%20)*)");

            Dictionary<string, List<string>> allQueries =
                                new Dictionary<string, List<string>>();

            StringBuilder result = new StringBuilder();
            string inputLine = Console.ReadLine();
            while (inputLine != "END")
            {
                string[] queryInfo = inputLine
                    .Split(new[] { '&', '?' }, StringSplitOptions.RemoveEmptyEntries);

                foreach (string pair in queryInfo)
                {
                    if (!validPair.IsMatch(pair))
                    {
                        continue;
                    }

                    string[] pairInfo = pair.Split('=');

                    string key = pairInfo[0];
                    string value = pairInfo[1];

                    key = spaces.Replace(key, " ").Trim();
                    value = spaces.Replace(value, " ").Trim();

                    if (!allQueries.ContainsKey(key))
                    {
                        allQueries.Add(key, new List<string>());
                    }

                    allQueries[key].Add(value);
                }

                foreach (KeyValuePair<string, List<string>> pair in allQueries)
                {
                    result.Append($"{pair.Key}=[{string.Join(", ", pair.Value)}]");
                }

                result.Append("\r\n");

                allQueries.Clear();

                inputLine = Console.ReadLine();
            }

            Console.WriteLine(result.ToString().Trim('\r', '\n'));
        }
    }
}