Monty Hall 让我们做一笔 Java 模拟 10000 次迭代

Question

我要创建一个运行 Monty Hall 的程序，让我们进行 10000 次交易并输出以下统计数据：

• 胜负数
• 玩家切换并赢得与留下并保持的次数 获胜。
• 显示切换和停留时的胜负百分比。

切换和获胜与保持和获胜的期望输出应该在切换时的 2/3 左右。我得到了，但只有一半；切换时为 33%，停留时为 16%。我不知道为什么其他 50% 没有出现。 很确定它与我的第二个 switch 语句有关，但无法弄清楚（可能是由于缺乏睡眠）。

我做错了什么？提前致谢。

                int iterations; 
                for (iterations = 0; iterations < 10000; iterations++)
                {
                    int prizeIs = (int) ((Math.random() * 3) + 1);  
                    int compChoice = (int) ((Math.random() * 3) + 1);
                    int zonkIs = 0;
                    if ( prizeIs == compChoice )
                    {
                            boolean chooseFirstZonk = Math.random() < 0.5; // 50% chance
                            switch ( prizeIs ) 
                            {
                                case 1: if ( chooseFirstZonk ) 
                                        {
                                            zonkIs = 2;
                                        }    
                                        else 
                                        {
                                            zonkIs = 3;
                                        }
                                        break;
                                case 2: if ( chooseFirstZonk ) 
                                        {
                                            zonkIs = 1;
                                        }    
                                        else 
                                        {
                                            zonkIs = 3;
                                        }
                                        break;
                                case 3: if ( chooseFirstZonk ) 
                                        {
                                            zonkIs = 1;
                                        } 
                                        else 
                                        {
                                            zonkIs = 2;
                                        }
                                        break;
                                }
                        }
                        else if (prizeIs == 1 && compChoice == 2)
                        {
                            zonkIs = 3; 
                        }
                        else if (prizeIs == 1 && compChoice == 3 )
                        {
                            zonkIs = 2; 
                        }
                        else if (prizeIs == 2 && compChoice == 1 )
                        {
                            zonkIs = 3;
                        }
                        else if (prizeIs == 2 && compChoice == 3 )
                        {
                            zonkIs = 1;
                        }
                        else if (prizeIs == 3 && compChoice == 1 )
                        {
                            zonkIs = 2;
                        }
                        else if (prizeIs == 3 && compChoice == 2 )
                        {
                            zonkIs = 1;
                        }

                         //generating a 1 or 2 to decide whether to switch doors or not
                        int switchDoor = (int) (1 +  (Math.random() * 2));

                        switch ( switchDoor ) 
                        {
                            //not switching doors 
                            case 1:  
                                    {
                                        //since we didnt switch 
                                        //if compchoice == prize 
                                        //then thats considered a win 
                                        //for not switching 
                                        if (compChoice == prizeIs)
                                        {
                                            noSwitch++;
                                            wins++;
                                            games++;
                                        }
                                        //if we didnt win 
                                        //the games will be incremented by 1
                                        //later to use to calculate the losses 
                                        else
                                        {
                                            games++;
                                        }
                                    }    
                                    break;
                            //switch door
                            case 2:
                                    {
                                        //since we did switch 
                                        //if compchoice == prize 
                                        //then thats considered a loss 
                                        //because were switching 
                                        //to the door that has a zonk 
                                        if (compChoice == prizeIs)
                                        {
                                            games++;
                                        }

                                        //if compchoice != prize 
                                        //then thats considered a win 
                                        //because were switching from the door 
                                        //with a zonk to the door with the prize 
                                        else if(compChoice != prizeIs)
                                        {

                                            switches++;
                                            wins++;
                                            games++;
                                        }

                                    }
                        }
                if (iterations == 10000)
                {

                    double percentage = 100.0 * (switches/games);
                    double noswitchpercentage = 100.0 *(noSwitch/games);
                    System.out.println( "Switch percentage : " + percentage);
                    System.out.println( "No Switch percentage : " + noswitchpercentage);
                    System.out.println( "wins : "+ wins);
                    System.out.println("losses : " + (games - wins));
                    break;
                }

Answer 1

当玩家获胜时，您只会增加 switch/noswitch。将 switch/noswitch 增量移到 if 之外，最好将游戏增量移到整个 switch 块之外，以免重复。

... 或者我不太明白这些变量的用途。因为这将为您带来 50% 的游戏。

如果您真的想知道每个策略的胜率，您需要存储您使用每个策略的次数，以及该策略的胜率，这比您当前存储的要多一件事。然后计算是wins_with_strategy/plays_with_strategy，而不是除以总游戏数。