Adv2016/D21.1/Program.cs

using System;
using System.Collections;
using System.IO;
using System.Linq;

namespace D21._1
{
    public class R : StreamReader, IEnumerable
    {
        public R(Stream stream) : base(stream) { }
        public IEnumerator GetEnumerator()
        {
            while (true)
            {
                var line = ReadLine();
                if (line == null) break;
                yield return line;
            }
        }
    }
    public class Program
    {
        public static char[] Swap(char[] input, int x, int y)
        {
            var result = input.Clone() as char[];
            var tmp = result[x];
            result[x] = result[y];
            result[y] = tmp;
            return result;
        }

        public static char[] Swap(char[] input, char x, char y)
        {
            var result = new char[input.Length];

            for (var i = 0; i < input.Length; i++)
            {
                if (input[i] == x) result[i] = y;
                else if (input[i] == y) result[i] = x;
                else result[i] = input[i];
            }

            return result;
        }

        public static char[] RotateLeft(char[] input, int x) => Rotate(input, 1, x);

        public static char[] RotateRight(char[] input, int x) => Rotate(input, -1, x);

        static char[] Rotate(char[] input, int dir, int x)
        {
            var result = new char[input.Length];

            for (var i = 0; i < input.Length; i++)
            {
                int source = i + (dir * x);
                while (source < 0) source += input.Length;
                while (source >= input.Length) source -= input.Length;
                result[i] = input[source];
            }

            return result;
        }

        public static int IndexOf(char[] input, char l)
        {
            int index = -1;
            for (int i = 0; i < input.Length; i++)
            {
                char c = input[i];
                if (c == l)
                {
                    index = i;
                    break;
                }
            }
            return index;
        }

        public static char[] Rotate(char[] input, char x)
        {
            var index = IndexOf(input, x);
            if (index == -1) throw new Exception();
            return RotateRight(input, (index >= 4 ? index + 2 : index + 1));
        }

        public static char[] Reverse(char[] input, int x, int y)
        {
            var result = new char[input.Length];

            for (var i = 0; i < x; i++) result[i] = input[i];
            for (int i = x, j = y; i <= y; i++, j--) result[i] = input[j];
            for (var i = y + 1; i < input.Length; i++) result[i] = input[i];

            return result;
        }

        public static char[] Move(char[] input, int x, int y)
        {
            var result = input.Clone() as char[];

            if (x < y) Array.Copy(result, x + 1, result, x, y - x);
            else Array.Copy(result, y, result, y + 1, x - y);

            result[y] = input[x];

            return result;
        }

        static void Main(string[] args)
        {
            var scrambling = "abcdefgh".ToCharArray();

            using (var file = new R(File.OpenText(args[0]).BaseStream))
            {
                foreach (string line in file)
                {
                    if (line.StartsWith("swap position "))
                    {
                        var i = int.Parse(line.Split(" ")[2]);
                        var j = int.Parse(line.Split(" ")[5]);
                        scrambling = Swap(scrambling, i, j);
                    }
                    else if (line.StartsWith("swap letter "))
                    {
                        var i = line.Split(" ")[2][0];
                        var j = line.Split(" ")[5][0];
                        scrambling = Swap(scrambling, i, j);
                    }
                    else if (line.StartsWith("rotate right "))
                    {
                        var i = int.Parse(line.Split(" ")[2]);
                        scrambling = RotateRight(scrambling, i);
                    }
                    else if (line.StartsWith("rotate left "))
                    {
                        var i = int.Parse(line.Split(" ")[2]);
                        scrambling = RotateLeft(scrambling, i);
                    }
                    else if (line.StartsWith("rotate based on position of letter "))
                    {
                        scrambling = Rotate(scrambling, line.Last());
                    }
                    else if (line.StartsWith("reverse positions "))
                    {
                        var i = int.Parse(line.Split(" ")[2]);
                        var j = int.Parse(line.Split(" ")[4]);
                        scrambling = Reverse(scrambling, i, j);
                    }
                    else if (line.StartsWith("move position "))
                    {
                        var i = int.Parse(line.Split(" ")[2]);
                        var j = int.Parse(line.Split(" ")[5]);
                        scrambling = Move(scrambling, i, j);
                    }
                }
            }

            Console.WriteLine(scrambling);
        }
    }
}