// using System.Collections.Frozen;
using System.Diagnostics;
using System.Text;

internal class Program
{
    static char[] templateWord = "камарилья".ToCharArray();
    static HashSet<string> RussianNouns;


    private static void Main(string[] args)
    {
        Console.WriteLine("Hello, World!");

        RussianNouns = File.ReadAllLines("russian_nouns.txt").ToHashSet();
        var sw = Stopwatch.StartNew();
        List<string> generated = GetWords();
        Console.WriteLine(string.Join(',', generated));

        Console.WriteLine($"finish! {sw.ElapsedMilliseconds}");

    }

    private static List<string> GetWords()
    {
        int n = templateWord.Length;
        int m = 6;
        int[] arr = new int[n];

        for (int i = 0; i < n; i++)
            arr[i] = i + 1;

        //Print(a, m);
        List<string> generated = new(1000);

        while (NextSet(arr, n, m))
        {
            // var ww = BuildWord(arr, m);
            int[] arrTarget = new int[m];

            Array.Copy(arr, arrTarget, m);
            //Print(arrTarget);
            var genWords = GetPermutations(arrTarget, m).Select(x => BuildWord2(x.ToArray()));
            foreach (var ww in genWords)
            {
                if (RussianNouns.Contains(ww) && !generated.Contains(ww))
                    generated.Add(ww);
            }
        }

        return generated;
    }

    static bool NextSet(int[] arry, int n, int m)
    {
        int k = m;
        for (int i = k - 1; i >= 0; --i)
            if (arry[i] < n - k + i + 1)
            {
                ++arry[i];
                for (int j = i + 1; j < k; ++j)
                    arry[j] = arry[j - 1] + 1;
                return true;
            }
        return false;
    }

    static IEnumerable<IEnumerable<T>>
        GetPermutations<T>(IEnumerable<T> list, int length)
    {
        if (length == 1) return list.Select(t => new T[] { t });

        return GetPermutations(list, length - 1)
            .SelectMany(t => list.Where(e => !t.Contains(e)),
                (t1, t2) => t1.Concat(new T[] { t2 }));
    }

    static void Print(int[] a) => Console.WriteLine( $"[{string.Join(',',a)}]");

    static string BuildWord(int[] a, int k) =>
        new string(a[0..k].Select(x => templateWord[x - 1]).ToArray());

    static string BuildWord2(int[] a)
    {
        int k = a.Length;
        var res = new StringBuilder(k);
        for (int i = 0; i < k; i++)
        {
            res.Append(templateWord[a[i] - 1]);
        }
        return res.ToString();
    }
}