Day4, part 1,2

    private void Day4Part1()
    {
        string[] lines = File.ReadAllLines("C:/input.txt");

        long finalSum = 0;

        Dictionary<char, int> charCount = new Dictionary<char, int>();

        for(int i = 0; i < lines.Length; i++)
        {
            string entry = lines[i];
            string entryChecksum = entry.Substring(entry.LastIndexOf("[") + 1, 5);
            int sectorId = int.Parse(entry.Substring(entry.LastIndexOf("-") + 1, entry.LastIndexOf("[") - entry.LastIndexOf("-") - 1));
            string letters = new string(entry.Substring(0, entry.LastIndexOf('-')).Replace("-", "").OrderBy(c => c).ToArray());

            charCount.Clear();
            for(int j = 0; j < letters.Length; j++)
            {
                if(!charCount.ContainsKey(letters[j]))
                {
                    charCount.Add(letters[j], 1);
                }
                else
                {
                    charCount[letters[j]]++;
                }
            }

            string checksum = new string(charCount.OrderByDescending(r => r.Value).Select(r => r.Key).Take(5).ToArray());
            if(checksum == entryChecksum)
            {
                finalSum += sectorId;
            }
        }
        Debug.Log(finalSum);
    }

    private void Day4Part2()
    {
        string[] lines = File.ReadAllLines("C:/input.txt");

        for(int i = 0; i < lines.Length; i++)
        {
            string entry = lines[i];
            string entryChecksum = entry.Substring(entry.LastIndexOf("[") + 1, 5);
            int sectorId = int.Parse(entry.Substring(entry.LastIndexOf("-") + 1, entry.LastIndexOf("[") - entry.LastIndexOf("-") - 1));
            string letters = entry.Substring(0, entry.LastIndexOf('-'));

            string location = "";
            for(int j = 0; j < letters.Length; j++)
            {
                location += Shift(letters[j], sectorId);
            }
            if(location.Contains("pole") && location.Contains("north"))
            {
                Debug.Log(sectorId);
            }
        }
    }

    private char Shift(char c, int count)
    {
        count = count % 26;

        int ac = (int)c - 97;
        ac += count;
        ac = ac % 26;
        ac += 97;
        return (char)ac;
    }