EightQueens/EightQueens.cs

namespace EightQueens;

public struct Coord(int x, int y)
{
    public int X { get; set; } = x;
    public int Y { get; set; } = y;
};

public class Board {

    private List<Coord> Figures {get;set;} = [];

    public bool IsFieldBusy(int x, int y)
    {
        return Figures.Any(f => x==f.X && y==f.Y);
    }

    public void Add(int x, int y)
    {
        var pos = new Coord(x, y);

        if (IsFieldBusy(x, y)) return;
        Figures.Add(pos);
    }

    public void Remove(int x, int y)
    {
        var pos = new Coord(x, y);
        Figures.Remove(pos);
    }

    public void Clear()
    {
        Figures.Clear();
    }

    public List<Coord> GetFigures()
    {
        return Figures;
    }

    public void Draw()
    {
        for (int x = 0; x < 9; x++)
        {
            string row = "";
            for (int y = 0; y < 9; y++)
            {
                if (x + y == 0)
                {
                    row += " ";
                }
                else if (y == 0)
                {
                    row += $"{x}";
                }
                else if (x == 0)
                {
                    row += $"{y}";
                }
                else if (IsFieldBusy(x, y))
                {
                    row += "O";
                }
                else
                {
                    row += "#";
                }
                row+=" ";
            }
            Console.WriteLine(row);
        }

    }

    public int Count()
    {
        return Figures.Count;
    }

    public bool IsFieldSafe(int row, int col)
    {
        var figs = Figures.Where(f => !(row==f.X && col==f.Y)).ToList();

        foreach (var fig in figs)
        {
            if (fig.X == row || fig.Y == col) return false;
            if (Math.Abs(fig.X - row) == Math.Abs(fig.Y - col)) return false;
        }

        return true;
    }

    public bool IsBoardSafe()
    {
        foreach (var fig in Figures)
        {
            if (!IsFieldSafe(fig.X, fig.Y)) return false;
        }
        return true;
    }
}