Adventofcode Day 4 - Challenge 1

adventofcode-day4-1.cs

using System;
using System.IO;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using System.Linq;

namespace ConsoleApplication
{
    public class Program
    {
        public static void Main(string[] args)
        {
            using(var input = File.OpenText("input.txt")){
                string line;
                var sum = 0;
                while((line = input.ReadLine()) != null)
                {
                    var room = new Room(line);
                    if(room.IsValidRoomName()){
                        sum += room.sectorid;
                    }
                }
                Console.WriteLine(sum);
            }
        }

    }

    public class Room{
        public Room(string encryptedname){
            this.parseEncryptedName(encryptedname);
        }
        public string name{
            get;
            set;
        }
        public int sectorid{
            get;
            set;
        }
        public string checksum{
            get;
            set;
        }
        public bool IsValidRoomName(){
            return this.checksum == this.CalculateCheckSum();
        }
        private string CalculateCheckSum(){
            return String.Join("",this.GetGroupsOfLetters(this.name));
        }
        private char[] GetGroupsOfLetters(string input){
            var groups = input.GroupBy(c => c).OrderByDescending(g => g.Count()).ThenBy(g => g.Key).Select(g=>g.Key).Take(5).ToArray();
            return groups;
        }
        private void parseEncryptedName(string encryptedname){
            var pattern = new Regex(@"(.*)\-(\d*)\[(\w*)\]");
            var match = pattern.Match(encryptedname);
            name = match.Groups[1].Value.Replace("-","");
            sectorid = Int32.Parse(match.Groups[2].Value);
            checksum = match.Groups[3].Value;
        }
    }
}