自己手写的24点程序（包含括号操作，可适应所有四张牌类型，输入用空格隔开，回车结束）

  1 import java.util.ArrayList;
  2 import java.util.Arrays;
  3 import java.util.HashSet;
  4 import java.util.Scanner;
  5 
  6 import javax.script.ScriptEngine;
  7 import javax.script.ScriptEngineManager;
  8 import javax.script.ScriptException;
  9 
 10 public class Main {
 11     public static void main(String[] args) throws ScriptException {
 12         Scanner sc = new Scanner(System.in);
 13         while(sc.hasNext()) {
 14             String in = sc.nextLine();
 15             //in = "j k q a";
 16             in = in.trim();
 17             String out = game(in);
 18             System.out.println(out);
 19         }
 20     }
 21 
 22     private static String game(String in) throws ScriptException {
 23         in = in.toUpperCase();
 24         String[] ins = in.split("[\\s]+");
 25         if(ins.length != 4) {return "ERROR";}
 26         for (int i = 0; i < ins.length; i++) {
 27             if(ins[i].equals("A")) {ins[i] = "1";}
 28             if(ins[i].equals("J")) {ins[i] = "11";}
 29             if(ins[i].equals("Q")) {ins[i] = "12";}
 30             if(ins[i].equals("K")) {ins[i] = "13";}
 31             if(ins[i].equals("JOKER")) {return "ERROR";}
 32         }
 33         System.out.println(Arrays.asList(ins));
 34         
 35         //四张牌排序
 36         String[] numloc = {"1234","1243","1423","1432","1324","1342",
 37                 "2134","2143","2314","2341","2413","2431",
 38                 "3124","3142","3412","3421","3241","3214",
 39                 "4123","4132","4213","4231","4321","4312"};
 40         int loc;
 41         String[] co = {"+","-","*","/"};
 42         ArrayList<String> list = new ArrayList<>();
 43         String[][] str = null;
 44         for (int nl = 0; nl < numloc.length; nl++) {
 45             str = new String[4][4];        
 46             for (int j = 0; j < 3; j++) {
 47                 loc = Integer.parseInt(""+numloc[nl].charAt(j))-1;
 48                 for (int j2 = 0; j2 < 4; j2++) {
 49                     str[j][j2] = ins[loc]+co[j2];
 50                 }
 51             }
 52             for (int j = 0; j < 4; j++) {
 53                 loc = Integer.parseInt(""+numloc[nl].charAt(3))-1;
 54                 str[3][j] = ins[loc];
 55             }
 56             
 57             //
 58             String a = "";
 59             for (int j1 = 0; j1 < 4; j1++) {
 60                 for (int j2 = 0; j2 < 4; j2++) {
 61                     for (int j3 = 0; j3 < 4; j3++) {
 62                         for (int j4 = 0; j4 < 4; j4++) {
 63                             a=a+str[0][j1]+str[1][j2]+str[2][j3]+str[3][j4];
 64                             list.add(a);
 65                             a="";
 66                         }
 67                     }
 68                 }
 69             }
 70         }
 71         
 72         //加括号，共计扩容6倍
 73         list = new ArrayList<>(new HashSet(list));
 74         ArrayList<String> list2 = new ArrayList<>();
 75         for (int i = 0; i < list.size(); i++) {
 76             String s = list.get(i);
 77             //记录符号位置
 78             int[] a = new int[3];
 79             int count = 0;
 80             for (int j = 0; j < s.length(); j++) {
 81                 if(s.charAt(j)==‘+‘||s.charAt(j)==‘-‘||s.charAt(j)==‘*‘||s.charAt(j)==‘/‘)
 82                 {a[count++] = j;}
 83             }
 84             //System.out.println(s);
 85             String ss ;
 86             //第一种
 87             ss = "("+s.substring(0,a[1])+")"+s.substring(a[1], s.length());
 88             list2.add(ss);
 89             //第二种
 90             ss = "("+s.substring(0,a[2])+")"+s.substring(a[2], s.length());
 91             list2.add(ss);
 92             //第三种
 93             ss = s.substring(0,a[0]+1)+"("+s.substring(a[0]+1, a[2])+")"+s.substring(a[2],s.length());
 94             list2.add(ss);
 95             //第四种
 96             ss = s.substring(0,a[0]+1)+"("+s.substring(a[0]+1, s.length())+")";
 97             list2.add(ss);
 98             //第五种
 99             ss = s.substring(0,a[1]+1)+"("+s.substring(a[1]+1, s.length())+")";
100             list2.add(ss);
101             //第六种，双括号
102             ss = "("+s.substring(0,a[1])+")"+s.substring(a[1],a[1]+1)+"("+s.substring(a[1]+1, s.length())+")";
103             list2.add(ss);
104             
105             //System.out.println(list2);
106             //System.out.println("");
107             
108         }
109         list = new ArrayList<>(new HashSet(list));
110         list.addAll(list2);
111         System.out.println(list);
112         //System.out.println(list.size());
113         for (int i = 0; i < list.size(); i++) {
114             
115             Object d = null;
116             ScriptEngine se = new ScriptEngineManager().getEngineByName("JavaScript");
117             d = (Object) se.eval(list.get(i));
118             //System.out.println(i+"  "+d);
119             double result = 24D;
120             Double re = Double.valueOf(""+d);
121             if ( re>(result-0.0001) && re<(result+0.0001) ) {System.out.println("个数:"+list.size()+" "+list2.size());return "结果："+list.get(i); }
122             
123         }
124         System.out.println("个数:"+list.size()+" "+list2.size());
125         return "NONE";
126     }
127 }