4.Files

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

namespace _04.Files
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            //Regex rgxFilenames = new Regex(@"(?'fullPath'(?'root'[A-Za-z]+)(?:\\?[A-Za-z]+\\)+?(?'fileName'[A-za-z]+\.(?'extension'[A-Za-z]+)));(?'fileSize'\d+)");
            Dictionary<string, long> files = ReadFiles(n);
            string query = Console.ReadLine();
            Regex rgxQuery = new Regex(@"(?'extension'[A-Za-z]+) in (?'root'.+)");
            Match m = rgxQuery.Match(query);
            string extension = m.Groups["extension"].Value;
            string root = m.Groups["root"].Value;
            Dictionary<string, long> filesToPrint = files
                                                  .Where(file => MeetsConditions(file.Key, root, extension))
                                                  .Select(a => RemoveDirectory(a))
                                                  .OrderByDescending(a => a.Value)
                                                  .ThenBy(a => a.Key)
                                                  .ToDictionary(a => a.Key, a => a.Value);
            if (filesToPrint.Count == 0)
            { Console.WriteLine("No"); return; }
            foreach (var file in filesToPrint)
            {
                Console.WriteLine($"{file.Key} - {file.Value} KB");
            }
        }

        private static Dictionary<string, long> ReadFiles(int n)
        {
            Dictionary<string, long> files = new Dictionary<string, long>();
            Regex rgxFiles = new Regex(@"^(?'fullPath'(?'root'[^\\]+)\\(?:[^\\]+\\)*?(?'fileName'[^\\]+\.(?'extension'[^\\]+)));(?'fileSize'[\d]+)$");
            for (int i = 0; i < n; i++)
            {
                try
                {
                    string inputLine = Console.ReadLine();
                    Match m = rgxFiles.Match(inputLine);
                    string path = m.Groups["fullPath"].Value;
                    long fileSize = long.Parse(m.Groups["fileSize"].Value);
                    files[path] = fileSize;
                }
                catch (Exception)
                {
                }
            }
            return files;
        }

        private static bool MeetsConditions(string fileName, string root, string extension)
        {
            string fileRoot = fileName.Substring(0, root.Length);
            string fileExtension = GetExtension(fileName);
            if (fileRoot == root && fileExtension == extension)
            {
                return true;
            }
            return false;
        }

        private static string GetExtension(string fileName)
        {
            return new string(fileName.Reverse().TakeWhile(a => a != '.').Reverse().ToArray());
        }

        private static KeyValuePair<string, long> RemoveDirectory(KeyValuePair<string, long> a)
        {
            string removed = new string(a.Key.Reverse().TakeWhile(letter => letter != '\\').Reverse().ToArray());
            return new KeyValuePair<string, long>(removed, a.Value);
        }
    }
}