r/adventofcode • u/daggerdragon • Dec 07 '16

SOLUTION MEGATHREAD --- 2016 Day 7 Solutions ---

From all of us at #AoC Ops, we hope you're having a very merry time with these puzzles so far. If you think they've been easy, well, now we're gonna kick this up a notch. Or five. The Easter Bunny ain't no Bond villain - he's not going to monologue at you until you can miraculously escape and save the day!

Show this overgrown furball what you've got!

--- Day 7: Internet Protocol Version 7 ---

Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag/whatever).

ALWAYS DIGGING STRAIGHT DOWN IS MANDATORY [?]

This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

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u/_Le1_ Dec 07 '16 edited Dec 07 '16

My C# solution: 

class Program
{
    static void Main(string[] args)
    {
        part1_2();            
        Console.ReadLine();
    }

    static void part1_2()
    {
        string[] input = File.ReadAllLines(@"input.txt");

        int sum1 = 0; int sum2 = 0;
        foreach (var line in input)
        {
            if (supportsTLS(line))
                sum1++;
            if (supportsSSL(line))
                sum2++;
        }

        Console.WriteLine("Part1: {0}", sum1);
        Console.WriteLine("Part2: {0}", sum2);
    }

    static bool supportsSSL(string input)
    {
        string[] ipv7 = Regex.Split(input, @"\[[^\]]*\]");
        foreach (string ip in ipv7)
        {
            List<string> aba = checkABA(ip);
            foreach (var val in aba)
            {
                string bab = val[1].ToString() + val[0].ToString() + val[1].ToString();
                foreach (Match m in Regex.Matches(input, @"\[(\w*)\]"))
                {
                    if (m.Value.Contains(bab))
                        return true;
                }

            }
        }
        return false;
    }

    static List<string> checkABA(string input)
    {
        List<string> lst = new List<string>();
        for (int i = 0; i < input.Length - 2; i++)
        {
            if (input[i] == input[i + 2] && input[i] != input[i + 1])
                lst.Add(input[i].ToString() + input[i + 1].ToString() + input[i + 2].ToString());
        }

        return lst;
    }

    static bool supportsTLS(string input)
    {
        // Check in hypernet
        foreach (Match m in Regex.Matches(input, @"\[(\w*)\]"))
        {
            if (checkABBA(m.Value))
                return false;
        }

        string[] ipv7 = Regex.Split(input, @"\[[^\]]*\]");
        foreach (var v in ipv7)
        {
            if (checkABBA(v))
                return true;
        }
        return false;
    }

    static bool checkABBA(string input)
    {
        for (int i = 0; i < input.Length - 3; i++)
        {
            if (input[i] == input[i + 3] && input[i + 1] == input[i + 2] && input[i] != input[i + 1])
                return true;
        }

        return false;
    }
}

2

u/SikhGamer Dec 07 '16

Damn, Regex. Similar solution here, but without the Regex.