using System;
using System.IO;
using System.Diagnostics;
using Combinatorics.Collections;
using System.Collections.Generic;
using static System.Console;

namespace komvo
{
    class Program
    {
        static void Main(string[] args)
        {
            Beginig:

            List<Point> Points = new List<Point>();
            Random random = new Random();
            int pCount;
            Write("Введите количество точек: ");
            pCount = Convert.ToInt32(ReadLine());
            Stopwatch stopwatch = new Stopwatch();
            stopwatch.Start();

            for(int i = 0; i < pCount; i++)
            {
                int x = random.Next(80);
                int y = random.Next(70);
                Points.Add(new Point { X = x, Y = y });
                WriteLine("Точка {0} [{1};{2}]", i + 1, x, y);
            }
            WriteLine("\n");

            int matr = Points.Count;
            double[,] Matrix = new double[matr, matr];

            for (int i = 0; i < Points.Count; i++)
                for (int j = i; j < Points.Count - 1; j++)
                    Matrix[i, j + 1] = Matrix[j + 1, i] =
                        Math.Sqrt(Math.Pow(Points[j + 1].X - Points[i].X, 2) + Math.Pow(Points[j + 1].Y - Points[i].Y, 2));


            for (int i = 0; i < matr; i++)
            {
                for (int j = 0; j < matr; j++) Write("{0:00.00} ", Matrix[i, j]);
                WriteLine();
            }

            int[] toSwap = new int[Points.Count - 1];
            for (int i = 0; i <= toSwap.Length - 1; i++) toSwap[i] = i + 2;
            //for (int i = 0; i < toSwap.Length; i++) Write(toSwap[i]);         //debug

            int index = 0;
            double opLength = 0, prevResult = 0;
            string opRoute = string.Empty;

            Permutations<int> perm = new Permutations<int>(toSwap);
            foreach(IList<int> p in perm)
            {
                string route = string.Empty;
                for (int i = 0; i < toSwap.Length; i++) route += p[i].ToString() + ";";
                opLength = CountLength(Matrix, route);

                if (index != 0)
                {
                    if (opLength > prevResult)
                    {
                        opLength = prevResult;
                        opRoute = route;
                    }
                }
                else prevResult = opLength;

                index++;
            }

            WriteLine("\n\n1;{1}1 - оптимальный маршрут длинной {0:00.00}\nИз {2} маршрутов при {3} точках\nПосчитано за {4} мс\n\n",
                opLength, opRoute, Fact(Points.Count-1), Points.Count, stopwatch.ElapsedMilliseconds);
            stopwatch.Stop();

            Write("Ещё раз? (y/n)");
            char answer = Convert.ToChar(ReadLine());
            if (answer == 'y')
            {
                Points.Clear();
                goto Beginig;
            }
        }

        public static double CountLength(double[,] mtr, string route)
        {
            double result = 0;
            string[] index = route.Split(';');

            for (int j = 0; j < index.Length - 1; j++)
            {
                string dg = index[j];
                int db = int.Parse(index[j]) - 2;           //debug
                if (j == 0) result += mtr[0, int.Parse(index[j]) - 1];
                else if (j == index.Length - 1)
                {
                    result += mtr[int.Parse(index[j - 1]) - 2, int.Parse(index[j]) - 2];
                    result += mtr[0, int.Parse(index[j]) - 2];
                }
                else
                {
                    result += mtr[int.Parse(index[j - 1]) - 2, int.Parse(index[j]) - 2];
                }
            }
            return result;
        }

        public partial struct Point
        {
            public int X { get; set; }
            public int Y { get; set; }
        }

        static int Fact(int a) => a <= 1 ? 1 : a * Fact(a - 1);
    }
}