using System;

using System.Linq;

using System.Collections.Generic;

public record struct Cell(int x, int y);

​

public enum HitType

{

    Missed,

    Hit,

    HitAgain,

    Sink

}

​

public record struct HitResult(HitType hitType, string shipName);

public record Ship(List<Cell> cells, string shipName);

public record ShipLog(List<Cell> hits);

​

public interface IBattleship

{

    void Init(List<Ship> ships);

    HitResult[] DoHit(Cell cell);   

}

​

public class Battleship: IBattleship

{   

    private List<Ship> _ships = new List<Ship>();

    private Dictionary<string, HitType> _shipHits = new Dictionary<string, HitType>();

    void IBattleship.Init(List<Ship> ships)

    {       

        _ships =ships;

        _shipHits = _ships.ToDictionary(s => s.shipName, s => HitType.Missed);

    }

    HitResult TryHit(Ship ship, Cell cell)

    {

        var shipName = ship.shipName;

        var index = ship.cells.IndexOf(cell);

        if (index < 0)

        {

            _shipHits[shipName] = HitType.Missed;

            return new HitResult(HitType.Missed, shipName);

        }

        ship.cells.RemoveAt(index);

        if (ship.cells.Count == 0)

        {

            return new HitResult(HitType.Sink, shipName);

        }

        return _shipHits[shipName] == HitType.Hit

            ? new HitResult(HitType.HitAgain, shipName)

            : new HitResult(HitType.Hit, shipName);     

    }

    HitResult[] IBattleship.DoHit(Cell cell)

    {

        return _ships.Select(s => TryHit(s, cell)).ToArray();

    }       

}

​

public class Program

{

    public static void Main()

    {

        /*

        Here is the Battleship ground MxN and the set of ships. The ship is a collection of coordinates. 

        It might contain any number of coordinates (any number of parts of any shapes).

        The task is for a set (x, y) return “missed” if there is no ship on ground, “hit” if there is a ship,

        “hit again” if there is a square of ship already hit, 

        “sink SHIP” if there is a last last square of ship named SHIP 

        (you can assign any kind of name, but the name must be eventually unique for each ship).

        */

        IBattleship battleship = new Battleship();

        battleship.Init(new List<Ship>

        {

            new Ship([new Cell(0,0), new Cell(1,0)], "ship1"),

            new Ship([new Cell(0,1), new Cell(1,1)], "ship2")

        });

        var result = battleship.DoHit(new Cell(0, 0));      

        AssertTrue(() => result.Length == 2, "Must be two ships");

        AssertTrue(() => result.First(r => r.shipName == "ship1").hitType == HitType.Hit, "ship1 Must has Hit");        

        AssertTrue(() => result.First(r => r.shipName == "ship2").hitType == HitType.Missed, "ship1 Must has Hit");

        result = battleship.DoHit(new Cell(1, 0));      

        AssertTrue(() => result.First(r => r.shipName == "ship1").hitType == HitType.Sink, "ship1 Must has Sink");      

        result = battleship.DoHit(new Cell(1, 0));      

        AssertTrue(() => result.First(r => r.shipName == "ship1").hitType == HitType.Missed, "ship1 Must has Missed");      

        Console.WriteLine("No Errors");

    }

    static void AssertTrue(Func<bool> action, string message)

    {

        Console.WriteLine($"Checking for {message}");

        var res = action();

        if (res == false)

        {

            throw new Exception(message);

        }

    }

}

​

​

​

​