扑克牌计算24点的Java算法实现

以下是网上找来的代码，感谢原作者的精彩实现。(我已经记不得是什么时候在哪里看来的了，呵呵)

1. package com.chanson;
2. /*
3.  * @date   Aug 3, 2006
4.  * @project 学习
5.  * @company 个人
6.  * @author  chanson
7.  * @version 1.0
8.  */
9. import java.util.HashMap;
11. public class TwentyFour {
12.     
13.     private int[] aArray = new int[2];
14.     private int[] bArray = new int[2];
15.     private int[] cArray = new int[2];
16.     private int[] dArray = new int[2];
17.     
18.     /**
19.      * main方法
20.      * 
21.      * @param args
22.      */
23.     public static void main(String[] args) {
24.         new TwentyFour().dispose(3, 4, 5, 8);
25.     }
26.     
28.     public void dispose(int a, int b, int c, int d){
29.         aArray[0] = a;
30.         aArray[1] = 1;
31.         bArray[0] = b;
32.         bArray[1] = 1;
33.         cArray[0] = c;
34.         cArray[1] = 1;
35.         dArray[0] = d;
36.         dArray[1] = 1;
37.         core(aArray, bArray, cArray, dArray);
38.     }
39.     
40.     /**
41.      * 加
42.      */
43.     public  int[] plus(int[] a, int[] b){
44.         
45.         if(0 == a[1]){
46.             return new int[]{0,0};
47.         }
48.         if(0 == b[1]){
49.             return new int[]{0,0};
50.         }
51.         int denominator = leaseCommonMultiple(a[1],b[1]);
52.         
53.         return new int[]{denominator/a[1]*a[0] + denominator/b[1]*b[0] ,denominator};
54.     }
55.     
56.     /**
57.      * 减
58.      * @param a
59.      * @param b
60.      * @return
61.      */
62.     public  int[] reduce(int[] a, int[] b){
63.         if(0 == a[1]){
64.             return new int[]{0,0};
65.         }
66.         if(0 == b[1]){
67.             return new int[]{0,0};
68.         }
69.         int denominator = leaseCommonMultiple(a[1],b[1]);
70.         
71.         return new int[]{denominator/a[1]*a[0] - denominator/b[1]*b[0] ,denominator};
72.     }
73.     
74.     /**
75.      * 乘
76.      * @param a
77.      * @param b
78.      * @return
79.      */
80.     public  int[] multiply(int[] a, int[] b){
81.         return new int[]{a[0] * b[0], a[1] * b[1]};
82.     }
83.     
84.     /**
85.      * 除
86.      * @param a
87.      * @param b
88.      * @return
89.      */
90.     public  int[] divide(int[] a, int[] b){
91.         return new int[]{a[0] * b[1], a[1] * b[0]};
92.     }
93.     
94.     /**
95.      * 求最小公倍数
96.      * @param a
97.      * @param b
98.      * @return
99.      */
100.     public  int leaseCommonMultiple(int a, int b){
101.         return a*b/greatestCommonDivisor(a,b);
102.     }
103.     
104.     /**
105.      * 求最大公约数
106.      * @param a
107.      * @param b
108.      * @return
109.      */
110.     public  int greatestCommonDivisor(int a, int b) {
111.         if(0 == a && 0 == b){
112.             return 1;
113.         }
114.         if (0 == a) {
115.             return b;
116.         }
117.         if (0 == b) {
118.             return a;
119.         }
120.         if (a > b) {
121.             int c = a;
122.             a = b;
123.             b = c;
124.         }
125.         for (int c = a % b; c > 0; c = a % b) {
126.             a = b;
127.             b = c;
128.         }
129.         return b;
130.     }
131.     
132.     /**
133.      * 动态加载符号数
134.      * @param i
135.      * @param a
136.      * @param b
137.      * @return
138.      */
139.     public  int[] dispose(int i, int a[], int[] b){
140.         if(i == 0){
141.             return plus(a, b);
142.         }else if(i == 1){
143.             return reduce(a, b);
144.         }else if(i == 2){
145.             return multiply(a, b);
146.         }else{
147.             return divide(a, b);
148.         }
149.     }
150.     
151.     /**
152.      * 动态加载计算数
153.      * @param i
154.      * @param a
155.      * @param b
156.      * @param c
157.      * @param d
158.      * @return
159.      */
160.     public int[] number(int i, int[] a, int[] b, int[] c, int[] d){
161.         if(i == 0){
162.             return a;
163.         }else if(i == 1){
164.             return b;
165.         }else if(i == 2){
166.             return c;
167.         }else if(i == 3){
168.             return d;
169.         }else{
170.             return new int[]{0,1};
171.         }
172.     }
174.     /**
175.      * 核心算法部分
176.      * @param a
177.      * @param b
178.      * @param c
179.      * @param d
180.      */
181.     private  void core(int[] a, int[] b, int[] c, int[] d) {
182.         HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
183.         
184.         int count = 0;
185.         
186.         for(int i = 0; i < 4; i++){
187.             for(int j = 0; j < 4; j++){
188.                 for(int k = 0; k < 4; k++){
189.                     for(int m = 0; m < 4; m++){
190.                         for(int n = 0; n < 4; n++){
191.                             if(n == m)
192.                                 continue;
193.                             for(int o = 0; o < 4; o++){
194.                                 if(o == m || o == n)
195.                                     continue;
196.                                 for(int p = 0; p < 4; p++){
197.                                     if(p == m || p == n || p == o)
198.                                         continue;
199.                                     //类型1：A(A(A(a,b),c),d)
200.                                     int[] result1 = dispose(k,dispose(j,dispose(i,number(m,a,b,c,d),number(n,a,b,c,d)),number(o,a,b,c,d)),number(p,a,b,c,d));
201.                                     //类型2：A(A(a,A(b,c)),d)
202.                                     int[] result2 = dispose(k,dispose(i,number(m,a,b,c,d),dispose(j,number(n,a,b,c,d),number(o,a,b,c,d))),number(p,a,b,c,d));
203.                                     //类型3：A(a,A(b,A(c,d)))
204.                                     int[] result3 = dispose(i,number(m,a,b,c,d),dispose(j,number(n,a,b,c,d),dispose(k,number(o,a,b,c,d),number(p,a,b,c,d))));
205.                                     //类型4：A(a,A(A(b,c),d))
206.                                     int[] result4 = dispose(i,number(m,a,b,c,d),dispose(k,dispose(j,number(n,a,b,c,d),number(o,a,b,c,d)),number(p,a,b,c,d)));                                   
207.                                     //类型5：A(A(a,b),A(c,d))
208.                                     int[] result5 = dispose(j,dispose(i,number(m,a,b,c,d),number(n,a,b,c,d)),dispose(k,number(o,a,b,c,d),number(p,a,b,c,d)));
209.                                     if (0 != result1[1]) {
210.                                         if (result1[0] % result1[1] == 0) {
211.                                             if (result1[0] / result1[1] == 24) {
212.                                                 if ((!map.containsKey(new Integer(i)))|| (!map.containsKey(new Integer(j)))|| (!map.containsKey(new Integer(k)))) {
213.                                                     map.put(new Integer(i),new Integer(i));
214.                                                     map.put(new Integer(j),new Integer(j));
215.                                                     map.put(new Integer(k),new Integer(k));
216.                                                     count += 1;
217.                                                     System.out.println("((" + printNumber(m) + printSymbol(i) + printNumber(n) + ")" + printSymbol(j) + printNumber(o) + ")" + printSymbol(k) + printNumber(p));
218.                                                 }
219.                                             }
220.                                         }
221.                                     }
222.                                     if (0 != result2[1]) {
223.                                         if (result2[0] % result2[1] == 0) {
224.                                             if (result2[0] / result2[1] == 24) {
225.                                                 if ((!map.containsKey(new Integer(i)))|| (!map.containsKey(new Integer(j)))|| (!map.containsKey(new Integer(k)))) {
226.                                                     map.put(new Integer(i),new Integer(i));
227.                                                     map.put(new Integer(j),new Integer(j));
228.                                                     map.put(new Integer(k),new Integer(k));
229.                                                     count += 1;
230.                                                     System.out.println("(" + printNumber(m) + printSymbol(i) +"(" + printNumber(n) + printSymbol(j) + printNumber(o) + "))" + printSymbol(k) + printNumber(p));
231.                                                 }
232.                                             }
233.                                         }
234.                                     }
235.                                     if (0 != result3[1]) {
236.                                         if (result3[0] % result3[1] == 0) {
237.                                             if (result3[0] / result3[1] == 24) {
238.                                                 if ((!map.containsKey(new Integer(i))) || (!map.containsKey(new Integer(j)))|| (!map.containsKey(new Integer(k)))) {
239.                                                     map.put(new Integer(i),new Integer(i));
240.                                                     map.put(new Integer(j),new Integer(j));
241.                                                     map.put(new Integer(k),new Integer(k));
242.                                                     count += 1;
243.                                                     System.out.println(printNumber(m) + printSymbol(i) +"(" + printNumber(n) + printSymbol(j) + "(" + printNumber(o) +  printSymbol(k) + printNumber(p) + "))");
244.                                                 }
245.                                             }
246.                                         }
247.                                     }
248.                                     if (0 != result4[1]) {
249.                                         if (result4[0] % result4[1] == 0) {
250.                                             if (result4[0] / result4[1] == 24) {
251.                                                 if ((!map
252.                                                         .containsKey(new Integer(i)))|| (!map.containsKey(new Integer(j)))|| (!map.containsKey(new Integer(k)))) {
253.                                                     map.put(new Integer(i),new Integer(i));
254.                                                     map.put(new Integer(j),new Integer(j));
255.                                                     map.put(new Integer(k),new Integer(k));
256.                                                     count += 1;
257.                                                     System.out.println(printNumber(m) + printSymbol(i) +"((" + printNumber(n) + printSymbol(j) + printNumber(o) + ")" +  printSymbol(k) + printNumber(p) + ")");
258.                                                 }
259.                                             }
260.                                         }
261.                                     }
262.                                     if (0 != result5[1]) {
263.                                         if (result5[0] % result5[1] == 0) {
264.                                             if (result5[0] / result5[1] == 24) {
265.                                                 if ((!map.containsKey(new Integer(i)))|| (!map.containsKey(new Integer(j)))|| (!map.containsKey(new Integer(k)))) {
266.                                                     map.put(new Integer(i),new Integer(i));
267.                                                     map.put(new Integer(j),new Integer(j));
268.                                                     map.put(new Integer(k),new Integer(k));
269.                                                     count += 1;
270.                                                     System.out.println("(" + printNumber(m) + printSymbol(i) + printNumber(n) + ")" + printSymbol(j) + "(" + printNumber(o) + printSymbol(k) + printNumber(p) + ")");
271.                                                 }
272.                                             }
273.                                         }
274.                                     }
275.                                 }
276.                             }
277.                         }
278.                     }
279.                 }
280.             }
281.         }
282.         //总共几种答案，过滤了类似的答案 
283.         System.out.println("count: " + count);
284.     }
285.     
286.     public int printNumber(int i){
287.         if(i == 0){
288.             return aArray[0];
289.         }
290.         if(i == 1){
291.             return bArray[0];
292.         }
293.         if(i == 2){
294.             return cArray[0];
295.         }
296.         if(i == 3){
297.             return dArray[0];
298.         }
299.         return 0;
300.     }
301.     
302.     public String printSymbol(int i){
303.         
304.         if(i == 0){
305.             return " + ";
306.         }
307.         if(i == 1){
308.             return " - ";
309.         }
310.         if(i == 2){
311.             return " * ";
312.         }
313.         if(i == 3){
314.             return " / ";
315.         }
316.         return "";
317.     }
318. }