爱因斯坦的谜题

爱因斯坦的谜题：
    在一条街上有颜色互不相同的五栋房子，不同国籍的人分别住在这五栋房子力，每人抽不同品牌的香烟，喝不同的饮料，养不同的宠物。已知如下情况：
1.  英国人住红色房子里。
2.  瑞典人养狗。
3.  丹麦人喝茶。
4.  绿色房子坐落在白色房子的左面。
5.  绿色房子的主人喝咖啡。
6.  抽Pall Mall香烟的人养鸟。
7.  黄色房子的主人抽Dunhill香烟。
8.  挪威人住第一间房子。
9.  五座房子中间的那座的主人喝牛奶。
10. 抽Blends香烟的住在养猫人的隔壁。
11. 养马的人住在抽Dunhill香烟者的隔壁。
12. 抽Blue Master香烟的喝啤酒。
13. 德国人抽Prince香烟。
14. 挪威人住的房子在蓝色房子的隔壁。
15. 抽Blends香烟的人有一个喝水的邻居。
问：谁养鱼？
 
谜题的英文原文：
Let us assume that there are five houses of different colors next to each other on the same road.
In each house lives a man of a different nationality. Every man has his favorite drink, his
favorite brand of cigarettes, and keeps pets of a particular kind.

1.The Englishman lives in the red house.
2.The Swede keeps dogs.
3.The Dane drinks tea.
4.The green house is just to the left of the white one.
5.The owner of the green house drinks coffee.
6.The Pall Mall smoker keeps birds.
7.The owner of the yellow house smokes Dunhills.
8.The man in the center house drinks milk.
9.The Norwegian lives in the first house.
10.The Blend smoker has a neighbor who keeps cats.
11.The man who smokes Blue Masters drinks bier.
12.The man who keeps horses lives next to the Dunhill smoker.
13.The German smokes Prince.
14.The Norwegian lives next to the blue house.
15.The Blend smoker has a neighbor who drinks water.

The question to be answered is: Who keeps fish?


 这道迷题出自1981年柏林的德国逻辑思考学院。据说世界上只有2%的人能出答案。就连大名鼎鼎的爱因斯坦也成为此题大伤脑筋，所以这道题也经常被国内外知名公司用做面试题目，相信许多朋友都只做出过一个答案，今天就用计算机来看看答案：

 

000001    package my.code.reflectTest;
000002    
000003    
000009    public class WhoFeedsFish {
000010    
000011     private static final String problem = "爱因斯坦的推理题：\n\n" + "1．有5栋5种颜色的房子\n"
000012         + "2．每一位房子的主人国籍都不同\n" + "3．这五个人每人只喝一个牌子的饮料，只抽一个牌子的香烟，只养一种宠物\n"
000013         + "4．没有人有相同的宠物，抽相同牌子的烟，喝相同牌子的饮料\n\n" + "已知条件：\n" + "1．英国人住在红房子里\n"
000014         + "2．瑞典人养了一条狗\n" + "3．丹麦人喝茶\n" + "4．绿房子在白房子的左边\n" + "5．绿房子主人喝咖啡\n"
000015         + "6．抽pallmall烟的人养了一只鸟\n" + "7．黄房子主人抽dunhill烟\n"
000016         + "8．住在中间房子的人喝牛奶\n" + "9．挪威人住在第一间房子\n"
000017         + "10．抽Blue Master的人住在养猫人的旁边\n" + "11．养马人住在抽dunhill烟人的旁边\n"
000018         + "12．抽bluemaster烟的人喝啤酒\n" + "13．德国人抽prince烟\n" + "14．挪威人住在蓝房子旁边\n"
000019         + "15．抽Blue Master的人的邻居喝矿泉水\n\n" + "问题：谁养鱼？\n";
000020    
000021    
000024     public String getProblem() {
000025        return problem;
000026     }
000027    
000028     private static final int NATIONALITY_ENGLISH = 1;
000029     private static final int NATIONALITY_SWIDISH = 2;
000030     private static final int NATIONALITY_DAMARK = 3;
000031     private static final int NATIONALITY_NORWAY = 4;
000032     private static final int NATIONALITY_GERMAN = 5;
000033     private int[] nationalities = new int[5];
000034    
000035     private static final int COLOR_RED = 1;
000036     private static final int COLOR_GREEN = 2;
000037     private static final int COLOR_YELLOW = 3;
000038     private static final int COLOR_WHITE = 4;
000039     private static final int COLOR_BLUE = 5;
000040     private int[] colors = new int[5];
000041    
000042     private static final int PET_DOG = 1;
000043     private static final int PET_BIRD = 2;
000044     private static final int PET_CAT = 3;
000045     private static final int PET_HORSE = 4;
000046     private static final int PET_FISH = 5;
000047     private int[] pets = new int[5];
000048    
000049     private static final int DRINK_TEA = 1;
000050     private static final int DRINK_COFFEE = 2;
000051     private static final int DRINK_MILK = 3;
000052     private static final int DRINK_BEER = 4;
000053     private static final int DRINK_WATER = 5;
000054     private int[] drinks = new int[5];
000055    
000056     private static final int TOBACCO_PALLMALL = 1;
000057     private static final int TOBACCO_DUNHILL = 2;
000058     private static final int TOBACCO_BLUEMASTER = 3;
000059     private static final int TOBACCO_PRINCE = 4;
000060     private static final int TOBACCO_MIXED = 5;
000061     private int[] tobaccoes = new int[5];
000062    
000063     // 5*5的二维数组，答案就在其中：
000064     private int[][] key = { nationalities, colors, pets, drinks, tobaccoes };
000065    
000066     private static final int[][] values = { { 1, 2, 3, 4, 5 },
000067         { 1, 2, 3, 5, 4 }, { 1, 2, 4, 3, 5 }, { 1, 2, 4, 5, 3 },
000068         { 1, 2, 5, 3, 4 }, { 1, 2, 5, 4, 3 }, { 1, 3, 2, 4, 5 },
000069         { 1, 3, 2, 5, 4 }, { 1, 3, 4, 2, 5 }, { 1, 3, 4, 5, 2 },
000070         { 1, 3, 5, 2, 4 }, { 1, 3, 5, 4, 2 }, { 1, 4, 2, 3, 5 },
000071         { 1, 4, 2, 5, 3 }, { 1, 4, 3, 2, 5 }, { 1, 4, 3, 5, 2 },
000072         { 1, 4, 5, 2, 3 }, { 1, 4, 5, 3, 2 }, { 1, 5, 2, 3, 4 },
000073         { 1, 5, 2, 4, 3 }, { 1, 5, 3, 2, 4 }, { 1, 5, 3, 4, 2 },
000074         { 1, 5, 4, 2, 3 }, { 1, 5, 4, 3, 2 }, { 2, 1, 3, 4, 5 },
000075         { 2, 1, 3, 5, 4 }, { 2, 1, 4, 3, 5 }, { 2, 1, 4, 5, 3 },
000076         { 2, 1, 5, 3, 4 }, { 2, 1, 5, 4, 3 }, { 2, 3, 1, 4, 5 },
000077         { 2, 3, 1, 5, 4 }, { 2, 3, 4, 1, 5 }, { 2, 3, 4, 5, 1 },
000078         { 2, 3, 5, 1, 4 }, { 2, 3, 5, 4, 1 }, { 2, 4, 1, 3, 5 },
000079         { 2, 4, 1, 5, 3 }, { 2, 4, 3, 1, 5 }, { 2, 4, 3, 5, 1 },
000080         { 2, 4, 5, 1, 3 }, { 2, 4, 5, 3, 1 }, { 2, 5, 1, 3, 4 },
000081         { 2, 5, 1, 4, 3 }, { 2, 5, 3, 1, 4 }, { 2, 5, 3, 4, 1 },
000082         { 2, 5, 4, 1, 3 }, { 2, 5, 4, 3, 1 }, { 3, 1, 2, 4, 5 },
000083         { 3, 1, 2, 5, 4 }, { 3, 1, 4, 2, 5 }, { 3, 1, 4, 5, 2 },
000084         { 3, 1, 5, 2, 4 }, { 3, 1, 5, 4, 2 }, { 3, 2, 1, 4, 5 },
000085         { 3, 2, 1, 5, 4 }, { 3, 2, 4, 1, 5 }, { 3, 2, 4, 5, 1 },
000086         { 3, 2, 5, 1, 4 }, { 3, 2, 5, 4, 1 }, { 3, 4, 1, 2, 5 },
000087         { 3, 4, 1, 5, 2 }, { 3, 4, 2, 1, 5 }, { 3, 4, 2, 5, 1 },
000088         { 3, 4, 5, 1, 2 }, { 3, 4, 5, 2, 1 }, { 3, 5, 1, 2, 4 },
000089         { 3, 5, 1, 4, 2 }, { 3, 5, 2, 1, 4 }, { 3, 5, 2, 4, 1 },
000090         { 3, 5, 4, 1, 2 }, { 3, 5, 4, 2, 1 }, { 4, 1, 2, 3, 5 },
000091         { 4, 1, 2, 5, 3 }, { 4, 1, 3, 2, 5 }, { 4, 1, 3, 5, 2 },
000092         { 4, 1, 5, 2, 3 }, { 4, 1, 5, 3, 2 }, { 4, 2, 1, 3, 5 },
000093         { 4, 2, 1, 5, 3 }, { 4, 2, 3, 1, 5 }, { 4, 2, 3, 5, 1 },
000094         { 4, 2, 5, 1, 3 }, { 4, 2, 5, 3, 1 }, { 4, 3, 1, 2, 5 },
000095         { 4, 3, 1, 5, 2 }, { 4, 3, 2, 1, 5 }, { 4, 3, 2, 5, 1 },
000096         { 4, 3, 5, 1, 2 }, { 4, 3, 5, 2, 1 }, { 4, 5, 1, 2, 3 },
000097         { 4, 5, 1, 3, 2 }, { 4, 5, 2, 1, 3 }, { 4, 5, 2, 3, 1 },
000098         { 4, 5, 3, 1, 2 }, { 4, 5, 3, 2, 1 }, { 5, 1, 2, 3, 4 },
000099         { 5, 1, 2, 4, 3 }, { 5, 1, 3, 2, 4 }, { 5, 1, 3, 4, 2 },
000100         { 5, 1, 4, 2, 3 }, { 5, 1, 4, 3, 2 }, { 5, 2, 1, 3, 4 },
000101         { 5, 2, 1, 4, 3 }, { 5, 2, 3, 1, 4 }, { 5, 2, 3, 4, 1 },
000102         { 5, 2, 4, 1, 3 }, { 5, 2, 4, 3, 1 }, { 5, 3, 1, 2, 4 },
000103         { 5, 3, 1, 4, 2 }, { 5, 3, 2, 1, 4 }, { 5, 3, 2, 4, 1 },
000104         { 5, 3, 4, 1, 2 }, { 5, 3, 4, 2, 1 }, { 5, 4, 1, 2, 3 },
000105         { 5, 4, 1, 3, 2 }, { 5, 4, 2, 1, 3 }, { 5, 4, 2, 3, 1 },
000106         { 5, 4, 3, 1, 2 }, { 5, 4, 3, 2, 1 } };
000107    
000108     public void printKey() {
000109        for (int i = 0; i < 5; i++) {
000110         print("nationality", key[0][i]);
000111        }
000112        System.out.println();
000113        for (int i = 0; i < 5; i++) {
000114         print("color", key[1][i]);
000115        }
000116        System.out.println();
000117        for (int i = 0; i < 5; i++) {
000118         print("pet", key[2][i]);
000119        }
000120        System.out.println();
000121        for (int i = 0; i < 5; i++) {
000122         print("drink", key[3][i]);
000123        }
000124        System.out.println();
000125        for (int i = 0; i < 5; i++) {
000126         print("tobacco", key[4][i]);
000127        }
000128        System.out.println();
000129    
000130     }
000131    
000132     private void print(String item, int index) {
000133        if (false) {
000134        } else if ("nationality".equals(item)) {
000135         switch (index) {
000136         case 1:
000137            System.out.print("英国人\t");
000138            break;
000139         case 2:
000140            System.out.print("瑞典人\t");
000141            break;
000142         case 3:
000143            System.out.print("丹麦人\t");
000144            break;
000145         case 4:
000146            System.out.print("挪威人\t");
000147            break;
000148         case 5:
000149            System.out.print("德国人\t");
000150            break;
000151         }
000152        } else if ("color".equals(item)) {
000153         switch (index) {
000154         case 1:
000155            System.out.print("红房子\t");
000156            break;
000157         case 2:
000158            System.out.print("绿房子\t");
000159            break;
000160         case 3:
000161            System.out.print("黄房子\t");
000162            break;
000163         case 4:
000164            System.out.print("白房子\t");
000165            break;
000166         case 5:
000167            System.out.print("蓝房子\t");
000168            break;
000169         }
000170        } else if ("pet".equals(item)) {
000171         switch (index) {
000172         case 1:
000173            System.out.print("狗\t");
000174            break;
000175         case 2:
000176            System.out.print("鸟\t");
000177            break;
000178         case 3:
000179            System.out.print("猫\t");
000180            break;
000181         case 4:
000182            System.out.print("马\t");
000183            break;
000184         case 5:
000185            System.out.print("鱼\t");
000186            break;
000187         }
000188        } else if ("drink".equals(item)) {
000189         switch (index) {
000190         case 1:
000191            System.out.print("茶\t");
000192            break;
000193         case 2:
000194            System.out.print("咖啡\t");
000195            break;
000196         case 3:
000197            System.out.print("牛奶\t");
000198            break;
000199         case 4:
000200            System.out.print("啤酒\t");
000201            break;
000202         case 5:
000203            System.out.print("水\t");
000204            break;
000205         }
000206        } else if ("tobacco".equals(item)) {
000207         switch (index) {
000208         case 1:
000209            System.out.print("PALLMALL\t");
000210            break;
000211         case 2:
000212            System.out.print("DUNHILL\t");
000213            break;
000214         case 3:
000215            System.out.print("BLUEMASTER\t");
000216            break;
000217         case 4:
000218            System.out.print("PRINCE\t");
000219            break;
000220         case 5:
000221            System.out.print("Blue Master\t");
000222            break;
000223         }
000224        }
000225     }
000226    
000227     // 条件1：英国人住在红房子里 01
000228     private boolean check01() {
000229        for (int i = 0; i < nationalities.length; i++) {
000230         if (key[0][i] == NATIONALITY_ENGLISH) {
000231            if (key[1][i] != COLOR_RED) {
000232             return false;
000233            } else {
000234             return true;
000235            }
000236         }
000237        }
000238        return false;
000239     }
000240    
000241     // 条件2：瑞典人养了一条狗 02
000242     private boolean check02() {
000243        for (int i = 0; i < nationalities.length; i++) {
000244         if (key[0][i] == NATIONALITY_SWIDISH) {
000245            if (key[2][i] != PET_DOG) {
000246             return false;
000247            } else {
000248             return true;
000249            }
000250         }
000251        }
000252        return false;
000253     }
000254    
000255     // 条件4：绿房子在白房子的左边 1
000256     private boolean check1() {
000257        for (int i = 0; i < colors.length; i++) {
000258         if (key[1][i] == COLOR_GREEN) {
000259            for (int j = 0; j < colors.length; j++) {
000260             if (key[1][j] == COLOR_WHITE) {
000261                if (i > j) {
000262                 return false;
000263                } else {
000264                 return true;
000265                }
000266             }
000267            }
000268         }
000269        }
000270        return false;
000271     }
000272    
000273     // 条件8：住在中间房子的人喝牛奶 3
000274     private boolean check3() {
000275        return key[3][2] == DRINK_MILK ? true : false;
000276     }
000277    
000278     // 条件9：挪威人住在第一间房子 0
000279     private boolean check0() {
000280        if (key[0][0] != NATIONALITY_NORWAY) {
000281         return false;
000282        }
000283        return true;
000284     }
000285    
000286     // 14．挪威人住在蓝房子旁边 01
000287     private boolean check011() {
000288        for (int i = 0; i < nationalities.length; i++) {
000289         if (key[0][i] == NATIONALITY_NORWAY) {
000290            for (int j = 0; j < colors.length; j++) {
000291             if (key[1][j] == COLOR_BLUE) {
000292                if (Math.abs(i - j) == 1) {
000293                 return true;
000294                } else {
000295                 return false;
000296