21点玩法（二十一点必胜法原理）

一，游戏介绍1.1 游戏规则

21点又名黑杰克，该游戏由2到6个人玩，使用除大小王之外的52张牌，游戏者的目标是使手中的牌的点数之和不超过21点且尽量大。

1.2 牌点计算

A至10牌，按其原点数计算；J、Q、K都算作10点。

1.3 判断胜负

二十一点玩法规则和概率在二十一点游戏中，拥有最高点数的玩家获胜，其点数必须等于或低于21点；超过21点的玩家称为爆牌。拥有最高点数的玩家获胜，其点数必须等于或低于21点；超过21点之间判负。

二，游戏设计2.1 游戏流程

2.2 玩家类

由玩家自己选择是否继续拿牌。（输入Y继续拿牌，N为不拿牌）

2.3 AI类

简化AI逻辑，发牌后AI手牌和为4-8时继续拿牌，一直到17点或17点以上不再拿牌；因为此时再拿牌就有一半以上的概率超过21点。

三，参考代码using System;

namespace _21dian
{
using System;
using System.Collections.Generic;

namespace Game21Points
{
class Project
{
static void Main(string[] args)
{
Console.WriteLine("—– 游戏开始 —–");

// 扑克牌
List<int> cards = new List<int>()
{
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26,
27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52
};

// 创建对象
Poker poker = new Poker(cards);
Player player = new Player();
AIPlayer ai = new AIPlayer();

// –> 玩家入场
player.playerName = "Czhenya";
ai.playerName = "AI";

poker.AddPlayer(player);
poker.AddPlayer(ai);

// 事件关系绑定
poker.GameSratrHandler += player.GameStart;
poker.GameSratrHandler += ai.GameStart;

// 游戏开始
poker.GameStart();

// 每人发两张牌
poker.SendCard();
poker.SendCard();

// 询问取牌
poker.TaskCard();

Console.ReadKey();
}
}

abstract class AbsPlayer
{
public string playerName;
public bool IsContinueTakeCard = true;
public List<int> handCards = new List<int>();

public abstract void GameStart();

public virtual void SendCard(int card)
{
handCards.Add(card);
}

public abstract bool TakeCard();

public bool GameOver()
{
bool isGameOver;
if (HandCardsPoint > 21)
{
isGameOver = true;
}
else
{
isGameOver = !IsContinueTakeCard;
}
return isGameOver;
}

public int HandCardsPoint { get { return PokeTools.HandCardsSum(handCards); } }
}

class Player : AbsPlayer
{
public override void GameStart()
{
handCards.Clear();
Console.WriteLine("玩家整理了一下衣服，准备开局；");
}

public override void SendCard(int card)
{
handCards.Add(card);
Console.WriteLine("玩家发牌：" + PokeTools.PokerBrandByPoint(card));
}

public override bool TakeCard()
{
Console.WriteLine("当前您的手牌点数和为：" + HandCardsPoint);
Console.WriteLine("是否继续取牌(Y/N)？");
string readStr = Console.ReadLine();
// 输入Y取牌，其他为不取牌
IsContinueTakeCard = readStr.Equals("Y");
return IsContinueTakeCard;
}
}

class AIPlayer : AbsPlayer
{
public override void GameStart()
{
handCards.Clear();
Console.WriteLine("AI：清理一下内存，与之一战；");
}

public override void SendCard(int card)
{
base.SendCard(card);
Console.WriteLine("AI发牌：" + PokeTools.PokerBrandByPoint(card));
}

public override bool TakeCard()
{
// 手牌数点数小于17，就继续取牌
return HandCardsPoint < 17;
}
}

class Poker
{
List<AbsPlayer> players = new List<AbsPlayer>();
public Action GameSratrHandler;
public Action<int> SendCardHandler;
public Func<int, bool> TaskCardHandler;
// 发牌用
List<int> sendCards;

public Poker(List<int> cards)
{
// 复制一份发牌用
sendCards = new List<int>(cards);
}

public void AddPlayer(AbsPlayer player)
{
players.Add(player);
}

public void GameStart()
{
for (int i = 0; i < players.Count; i++)
{
if (!players[i].GameOver())
{
players[i].GameStart();
}
}
}

/// <summary>
/// 发牌 — 会剔除已经发过的牌
/// </summary>
public void SendCard()
{
for (int i = 0; i < players.Count; i++)
{
players[i].SendCard(SendOneCard());
}
}

int SendOneCard()
{
// 随机发一张牌
Random random = new Random();
int index = random.Next(0, sendCards.Count);
// 取到牌值
int cardPoint = sendCards[index];
// 从手牌中移除 –> 为避免发到相同的牌
sendCards.RemoveAt(index);

return cardPoint;
}

public void TaskCard()
{
for (int i = 0; i < players.Count; i++)
{
// 选择取牌后再发一张牌
if (players[i].TakeCard())
{
players[i].SendCard(SendOneCard());
}
Console.WriteLine(#34;玩家：{players[i].playerName} 手牌：{PokeTools.ShowHandCard(players[i].handCards)}");
}

if (!GameOver())
{
TaskCard();
}
}

public bool GameOver()
{
int playerCount = 0;
for (int i = 0; i < players.Count; i++)
{
if (!players[i].GameOver())
{
playerCount++;
}
}

bool isGameOver = playerCount <= 1;

if (isGameOver)
{
Console.WriteLine("游戏结束：");

List<AbsPlayer> playerList = new List<AbsPlayer>();
int maxPoint = 0;
for (int i = 0; i < players.Count; i++)
{
if (players[i].HandCardsPoint > 21)
{
Console.WriteLine(#34;玩家：{players[i].playerName} 爆牌了" );
}
else
{
playerList.Add(players[i]);
if (maxPoint < players[i].HandCardsPoint)
{
maxPoint = players[i].HandCardsPoint;
}
}
}

if (playerList.Count == 0)
{
Console.WriteLine("平局");
}
else if (playerList.Count == 1)
{

Console.WriteLine(#34;玩家：{playerList[0].playerName} 赢了");
}
else
{
for (int i = 0; i < playerList.Count; i++)
{
if (maxPoint == playerList[i].HandCardsPoint)
{
Console.WriteLine(#34;玩家：{playerList[i].playerName} 赢了");
}
}
}
}
return isGameOver;
}
}
}

class PokeTools
{
/// <summary>
/// 根据牌点返回牌名 如：14 ->红桃3
/// </summary>
/// <param name="card"></param>
/// <returns></returns>
public static string PokerBrandByPoint(int card)
{
if (card > 52 || card <= 0)
{
Console.WriteLine("不是扑克牌点");
return "不是扑克牌点";
}

string[] flowerColor = new string[4] { "黑桃", "红桃", "梅花", "方片" };
string[] points = new string[13] { "K", "A", "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q" };
int huaSe = (card – 1) / 13;
int point = card % 13;

// 返回花色 + 牌点 如：红桃3
return flowerColor[huaSe] + points[point];
}

/// <summary>
/// 手牌求和
/// </summary>
/// <param name="handCards"></param>
/// <returns></returns>
public static int HandCardsSum(List<int> handCards)
{
// "K", "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q"
int[] points = new int[13] { 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10 };
int sumRes = 0;

for (int i = 0; i < handCards.Count; i++)
{
sumRes += points[handCards[i] % 13];
}

return sumRes;
}

// 显示手牌
public static (string, string) ShowHandCard(List<int> handCards)
{
string resStr = "";
for (int i = 0; i < handCards.Count; i++)
{
resStr += PokeTools.PokerBrandByPoint(handCards[i]);
if (handCards.Count – 1 != i)
{
resStr += ",";
}
}

return (resStr, "牌点和:" + PokeTools.HandCardsSum(handCards));
}
}
}

测试结果：