Game.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Game15
{
    class Game
    {
        const int size =4;
        int[,] map = new int [size,size];
        int space_x, space_y;
        static Random rnd = new Random();
        public int count = 0;

        //public Game ()//(int size)
        //{
            //size = 4;
            //if (size < 2) size = 2;
            //if (size > 5) size = 5;
            //this.size = size;
            //map = new int[size, size];
        //}

        public void Start ()
        {
            for (int x = 0; x < size; x++)
                for (int y = 0; y < size; y++)
                    map[x, y] = CoordsToPosition(x, y) + 1;
            space_x = size - 1;
            space_y = size - 1;
            map[space_x, space_y] = 0;
        }
        public void Shift(int position)
        {
            int x, y;
            PositionToCoords(position, out x, out y);
            if (Math.Abs(space_x - x) + Math.Abs(space_y - y) != 1)
                return;
            map[space_x, space_y] = map[x, y];
            map[x, y] = 0;
            space_x = x;
            space_y = y;
        }

        public void ShiftRandom()
        {
            int a = rnd.Next(0, 4);
            int x = space_x;
            int y = space_y;
            switch(a)
            {
                case 0: x--; break;
                case 1: x++; break;
                case 2: y--; break;
                case 3: y++; break;
            }
            Shift(CoordsToPosition(x, y));
        }
        public bool CheckNumbers()
        {
            if (!(space_x == size - 1 && space_y == size - 1))
                return false;
            for (int x = 0; x < size; x++)
                for (int y = 0; y < size; y++)
                    if (!(x == size - 1 && y == size - 1))
                    if (map[x, y] != CoordsToPosition(x, y) + 1)
                        return false;
            return true;
         }

        public int GetNumber (int position)
        {
            int x, y;
            PositionToCoords(position, out x, out y);
            if (x < 0 || x >= size) return 0;
            if (y < 0 || y >= size) return 0;
            return map[x, y];
        }

        private int CoordsToPosition (int x, int y)
        {
            if (x < 0) x = 0;
            if (x > size - 1) x = size - 1;
            if (y < 0) y = 0;
            if (y > size - 1) y = size - 1;
            return y * size + x;
        }
        private void PositionToCoords(int position, out int x, out int y)
        {
            if (position < 0) position = 0;
            if (position > size*size - 1) position = size*size - 1;
            x = position % size;
            y = position / size;
        }
        public int CountSteps()
        {
           return count++;
        }
        public void RefreshCount()
        {
            count = 0;
        }
    }
}