Sorting

namespace _05.Sorting
{
    using System;
    using System.Collections.Generic;
    using System.Linq;

    public class Sorting
    {
        private static HashSet<string> used = new HashSet<string>();
        private static int result = -1;

        public static void Main(string[] args)
        {
            Console.ReadLine();

            char[] numbers = Console.ReadLine().Split().Select(char.Parse).ToArray();
            int lengthToReverse = int.Parse(Console.ReadLine());

            Queue<char[]> queue = new Queue<char[]>();
            queue.Enqueue(numbers);
            Queue<int> depths = new Queue<int>();
            depths.Enqueue(0);

            BFS(lengthToReverse, queue, depths);

            Console.WriteLine(result);
        }

        private static void BFS(int lengthToReverse, Queue<char[]> queue, Queue<int> depths)
        {
            while (queue.Count > 0)
            {
                var current = queue.Dequeue();
                var currentDepth = depths.Dequeue();

                if (result != -1)
                {
                    return;
                }

                if (IsSorted(current))
                {
                    result = currentDepth;
                    return;
                }

                used.Add(new string(current));

                for (int i = 0; i <= current.Length - lengthToReverse; i++)
                {
                    var reversed = current.Clone() as char[];
                    Array.Reverse(reversed, i, lengthToReverse);

                    if (IsSorted(reversed))
                    {
                        result = currentDepth + 1;
                        return;
                    }

                    if (!used.Contains(new string(reversed)))
                    {
                        queue.Enqueue(reversed);
                        depths.Enqueue(currentDepth + 1);
                    }
                }
            }
        }

        private static bool IsSorted(char[] numbers)
        {
            for (int i = 0; i < numbers.Length - 1; i++)
            {
                if (numbers[i] > numbers[i + 1])
                {
                    return false;
                }
            }

            return true;
        }
    }
}