0-9数字随意抽出4个数字用java编程怎么能够用四则运算还有括号得到24

最简单的就是四重循环，选出四个数之后，套入事先定好的模版，算出24搞定。
比如：
for(A=0; A<09; A++）{
  for(B) {
    for(C) {
      for(D) {
        //以下为各种模版
        if((A+B+C+D)==24) {
          print(A,B,C,D);
        } else if((A*B+C+D)==24) {
        } else if(xxx) {
        }
      }
    }
  }
}
当然还有更高的AI算法，那就懒得去想了

for(int i=0;i<4;i++){ //返回随机数，，，4改为7就是生成彩票6+1的了，我算了几次，，经常中五块的，哈哈，，

System.out.print((int)(9*Math.random()));

}

不过上面的for(A=0; A<09; A++）{
  for(B) {
    for(C) {
      for(D) {
        //以下为各种模版
        if((A+B+C+D)==24) {
          print(A,B,C,D);
        } else if((A*B+C+D)==24) {
        } else if(xxx) {
        }
      }
    }
  }
}
这种if-else的判断也太多了吧

数据规模大可以搜索来解,考虑适当的剪枝.PS.这里是J2EE版...

我找到一个比较好的算法，但是运行的时候出现java.lang.ArrayIndexOutOfBoundsException,应该是数组出现的问题但是我不知道如何修改程序还希望大家帮忙。程序如下
package tax;
/*
* 运算24点的工具
*
* Copyleft 2004 戴云杰 xdanger All Rights Reserved.
* http://www.xdanger.com
*
* 使用方式：
* 键入4个1-10的整数，即可显示所有结果等于24的计算方式
*/import java.io.*;
import java.lang.*;
//import java.applet.Applet;
//import java.awt.*;class Do24{
    // 目标值
    public final short DST_VALUE = ( short ) 24;
    // 输入值列表
    private short[] List = new short[4];
    // 结果列表
    private String[] Result = new String[1024];
    // 结果总数
    private short ResultNumber = 0;
    // 构造函数
    public Do24( short a, short b, short c, short d ){
        this.List[0] = a;
        this.List[1] = b;
        this.List[2] = c;
        this.List[3] = d;
        this.Result = this.countIt();
    }
    // 主函数
    public static void main( String[] args ){
        short a = Short.parseShort( args[0] );
        short b = Short.parseShort( args[1] );
        short c = Short.parseShort( args[2] );
        short d = Short.parseShort( args[3] );
        Do24 o = new Do24( a, b, c, d );
        o.printResult();    }
    // 开始计算
    public String[] countIt(){
        for( short l1 = 0; l1 < 4 ; l1++ ){
            short A;
            A = this.List[l1];
            for( short l2 = 0; l2 < 4 ; l2++){
                int B = this.List[l2];
                for( short l3 = 0; l3 < 4 ; l3++){
                    int C = this.List[l3];
                    for( short l4 = 0; l4<4 ; l4++){
                        int D = this.List[l4];
                        if( l1 != l2 && l2 != l3 && l3 != l4 && l4 != l1 && l1 != l3 && l2 != l4 ){
                            if( A + B + C + D == this.DST_VALUE )
                                this.putResult( A + "+" + B + "+" + C + "+" + D + "=" + this.DST_VALUE );
                            if( A + B + C - D == this.DST_VALUE )
                                this.putResult( A + "+" + B + "+" + C + "-" + D + "=" + this.DST_VALUE );
                            if( A + B - C - D == this.DST_VALUE )
                                this.putResult( A + "+" + B + "-" + C + "-" + D + "=" + this.DST_VALUE );
                            if( A - B - C - D == this.DST_VALUE )
                                this.putResult( A + "-" + B + "-" + C + "-" + D + "=" + this.DST_VALUE );
                            if( A * B * C * D == this.DST_VALUE )
                                this.putResult( A + "*" + B + "*" + C + "*" + D + "=" + this.DST_VALUE );
                            if( A * B * C - D == this.DST_VALUE )
                                this.putResult( A + "*" + B + "*" + C + "-" + D + "=" + this.DST_VALUE );
                            if( A * B - C - D == this.DST_VALUE )
                                this.putResult( A + "*" + B + "-" + C + "-" + D + "=" + this.DST_VALUE );
                            if( A * B - C * D == this.DST_VALUE )
                                this.putResult( A + "*" + B + "-" + C + "*" + D + "=" + this.DST_VALUE );
                            if( A * B * C + D == this.DST_VALUE )
                                this.putResult( A + "*" + B + "*" + C + "+" + D + "=" + this.DST_VALUE );
                            if( A * B + C + D == this.DST_VALUE )
                                this.putResult( A + "*" + B + "+" + C + "+" + D + "=" + this.DST_VALUE );
                            if( A * B + C * D == this.DST_VALUE )
                                this.putResult( A + "*" + B + "+" + C + "*" + D + "=" + this.DST_VALUE );
                            if( A * B + C - D == this.DST_VALUE )
                                this.putResult( A + "*" + B + "+" + C + "-" + D + "=" + this.DST_VALUE );
                            if( A - B * C * D == this.DST_VALUE )
                                this.putResult( A + "-" + B + "*" + C + "*" + D + "=" + this.DST_VALUE );
                            if( A + B - C * D == this.DST_VALUE )
                                this.putResult( A + "+" + B + "-" + C + "*" + D + "=" + this.DST_VALUE );
                            if( A * B * (C + D) == this.DST_VALUE )
                                this.putResult( A + "*" + B + "*(" + C + "+" + D + ")=" + this.DST_VALUE );
                            if( A * B * (C - D) == this.DST_VALUE )
                                this.putResult( A + "*" + B + "*(" + C + "-" + D + ")=" + this.DST_VALUE );
                            if( A * (B + C + D) == this.DST_VALUE )
                                this.putResult( A + "*(" + B + "+" + C + "+" + D + ")=" + this.DST_VALUE );
                            if( A * (B + C - D) == this.DST_VALUE )
                                this.putResult( A + "*(" + B + "+" + C + "-" + D + ")=" + this.DST_VALUE );
                            if( A * (B - C - D) == this.DST_VALUE )
                                this.putResult( A + "*(" + B + "-" + C + "-" + D + ")=" + this.DST_VALUE );
                            if( A - B * (C + D) == this.DST_VALUE )
                                this.putResult( A + "-" + B + "*(" + C + "+" + D + ")=" + this.DST_VALUE );
                            if( A - B * (C - D) == this.DST_VALUE )
                                this.putResult( A + "-" + B + "*(" + C + "-" + D + ")=" + this.DST_VALUE );
                            if( A * (B + C) - D == this.DST_VALUE )
                                this.putResult( A + "*(" + B + "+" + C + ")-" + D + "=" + this.DST_VALUE );
                            if( A * (B + C) + D == this.DST_VALUE )
                                this.putResult( A + "*(" + B + "+" + C + ")+" + D + "=" + this.DST_VALUE );
                            if( A * (B - C) - D == this.DST_VALUE )
                                this.putResult( A + "*(" + B + "-" + C + ")-" + D + "=" + this.DST_VALUE );
                            if( A * (B - C) + D == this.DST_VALUE )
                                this.putResult( A + "*(" + B + "-" + C + ")+" + D + "=" + this.DST_VALUE );
                            if( (A + B) * (C - D) == this.DST_VALUE )
                                this.putResult( "(" + A + "+" + B + ")*(" + C + "-" + D + ")=" + this.DST_VALUE );
                            if( (A + B) * (C + D) == this.DST_VALUE )
                                this.putResult( "(" + A + "+" + B + ")*(" + C + "+" + D + ")=" + this.DST_VALUE );
                            if( (A - B) * (C - D) == this.DST_VALUE )
                                this.putResult( "(" + A + "-" + B + ")*(" + C + "-" + D + ")=" + this.DST_VALUE );

if( B != 0 && A > B && A % B == 0 ){
                                if( A / B + C + D == this.DST_VALUE )
                                    this.putResult( A + "/" + B + "+" + C + "+" + D + "=" + this.DST_VALUE );
                                if( A / B + C - D == this.DST_VALUE )
                                    this.putResult( A + "/" + B + "+" + C + "-" + D + "=" + this.DST_VALUE );
                                 if( A / B - C - D == this.DST_VALUE )
                                    this.putResult( A + "/" + B + "-" + C + "-" + D + "=" + this.DST_VALUE );
                                if( A / B * C + D == this.DST_VALUE )
                                    this.putResult( A + "/" + B + "*" + C + "+" + D + "=" + this.DST_VALUE );
                                if( A / B + C * D == this.DST_VALUE )
                                    this.putResult( A + "/" + B + "+" + C + "*" + D + "=" + this.DST_VALUE );
                                if( A / B - C * D == this.DST_VALUE )
                                    this.putResult( A + "/" + B + "-" + C + "*" + D + "=" + this.DST_VALUE );
                                if( A / B * C - D == this.DST_VALUE )
                                    this.putResult( A + "/" + B + "*" + C + "-" + D + "=" + this.DST_VALUE );
                                if( A / B * C * D == this.DST_VALUE )
                                    this.putResult( A + "/" + B + "*" + C + "*" + D + "=" + this.DST_VALUE );
                                if( C * D - A / B == this.DST_VALUE )
                                    this.putResult( C + "*" + D + "-" + A + "/" + B + "=" + this.DST_VALUE );
                                if( C - D - A / B == this.DST_VALUE )
                                    this.putResult( C + "-" + D + "-" + A + "/" + B + "=" + this.DST_VALUE );
                                if( C + D - A / B == this.DST_VALUE )
                                    this.putResult( C + "+" + D + "-" + A + "/" + B + "=" + this.DST_VALUE );
                                if( C + D + A / B == this.DST_VALUE )
                                    this.putResult( C + "+" + D + "+" + A + "/" + B + "=" + this.DST_VALUE );
                                if( C * ( D - A / B) == this.DST_VALUE )
                                    this.putResult( C + "*(" + D + "-" + A + "/" + B + ")=" + this.DST_VALUE );
                                if( C * ( D + A / B) == this.DST_VALUE )
                                    this.putResult( C + "*(" + D + "+" + A + "/" + B + ")=" + this.DST_VALUE );
                                if( C * ( A / B - D) == this.DST_VALUE )
                                    this.putResult( C + "*(" + A + "/" + B + "-" + D + ")=" + this.DST_VALUE );
                                if( D != 0 && C > D && C % D == 0 ){
                                    if( (A / B) + (C / D) == this.DST_VALUE )
                                        this.putResult( "(" + A + "/" + B + ")+(" + C + "/" + D + "=" + this.DST_VALUE );
                                    if( (A / B) - (C / D) == this.DST_VALUE )
                                        this.putResult( "(" + A + "/" + B + ")-(" + C + "/" + D + "=" + this.DST_VALUE );
                                    if( (A / B) * (C / D) == this.DST_VALUE )
                                        this.putResult( "(" + A + "/" + B + ")*(" + C + "/" + D + "=" + this.DST_VALUE );
                                    if( A / B / D + C == this.DST_VALUE )
                                        this.putResult( A + "/" + B + "/" + D + "+" + C + "=" + this.DST_VALUE );
                                    if( A / B / D - C == this.DST_VALUE )
                                        this.putResult( A + "/" + B + "/" + D + "-" + C + "=" + this.DST_VALUE );
                                    if( A / B / D * C == this.DST_VALUE )
                                        this.putResult( A + "/" + B + "/" + D + "*" + C + "=" + this.DST_VALUE );
                                }
                            }
                        }
                    }
                }
            }
        }
        return this.Result;

    }

    // 打印结果
    public void printResult(){
        for( short i = 0; i < this.getResultNumber(); i++ )
            System.out.print( this.Result[i] + '\n' );
    }
    // 放入结果列表
    public void putResult( String result ){
        this.Result[this.getResultNumber()] = result;
        this.addResultNumber();
    }
    // 取得结果数目
    public short getResultNumber(){
        return this.ResultNumber;
    }
    // 设置结果数目
    private void setResultNumber( short number ){
        this.ResultNumber = number;
    }
    // 增加1个结果数目
    private void addResultNumber(){
        this.ResultNumber ++;
    }

}

很帅气的一个程序啊这个程序要求从命令行直接接受四个待算的数，java.lang.ArrayIndexOutOfBoundsException出现是由于你没有在运行时输满这四个数。
java Do24 1 2 3 4
看吧，有结果了但是程序是有问题的，像“1 3 4 6”和“3 3 8 8”这些比较经典的要用到分数的都没有结果，应该要改进啊。楼主还要程序么，我编了一个，回复就给你试试，正确输出所有结果应该没问题。

云那，我给你我写的一个用c++的吧，很好改成java的。
#include<iostream>
#include<string>
#include<vector>
#include<set>
using namespace std;
set<string>vs;
//author: JLU_faen of software
string gc(int n)
{
string s;
bool tag=false;
if(n<0){tag=true;n=-n;}
if(n==0){s="0";return s;}
while(n)
{
    s=char(n%10+'0')+s;
    n/=10;
    }
    if(tag)s='-'+s;
return s;
}
void g(vector<int> vi,string s)
{
if(vi.size()==1)
if(vi[0]==24)
{
vs.insert(s);
return;
}
else return;
for(int i=0;i<vi.size();i++)
for(int j=i+1;j<vi.size();j++)
{
    //if(j==i)continue;
vector<int>vit;
string snext;
for(int k=0;k<vi.size();k++)
if(k!=i&&k!=j)
vit.push_back(vi[k]);

vit.push_back(vi[i]+vi[j]);
snext=s+"   "+gc(vi[i])+"+"+gc(vi[j])+"="+gc(vi[i]+vi[j]);
g(vit,snext);
snext="";
vit.pop_back(); vit.push_back(vi[i]-vi[j]);
snext=s+"   "+gc(vi[i])+"-"+gc(vi[j])+"="+gc(vi[i]-vi[j]);
g(vit,snext);
vit.pop_back();
snext=""; vit.push_back(vi[i]*vi[j]);
snext=s+"   "+gc(vi[i])+"*"+gc(vi[j])+"="+gc(vi[i]*vi[j]);
g(vit,snext);
vit.pop_back();
snext=""; if(vi[j]&&vi[i]%vi[j]==0)
{
vit.push_back(vi[i]/vi[j]);
snext=s+"   "+gc(vi[i])+"/"+gc(vi[j])+"="+gc(vi[i]/vi[j]);
g(vit,snext);
vit.pop_back();
snext="";
}
if(vi[i]&&vi[j]%vi[i]==0)
{
vit.push_back(vi[j]/vi[i]);
snext=s+"   "+gc(vi[j])+"/"+gc(vi[i])+"="+gc(vi[j]/vi[i]);
g(vit,snext);
vit.pop_back();
snext="";
}
}
}
int main()
{
int a,b,c,d;
cout<<"please input four numbers:\n";
cin>>a>>b>>c>>d;
vector<int>vi;
vi.push_back(a);
vi.push_back(b);
vi.push_back(c);
vi.push_back(d);
string s;
g(vi,s);
if(vs.size())
{
set<string>::iterator p=vs.begin();
for(;p!=vs.end();p++)
cout<<*p<<endl;
}
else
cout<<"sorry the four numbers can't be done"<<endl;
int aa;
cin>>aa;
return 0;
}

public class Test24Point{
    public static void main(String[] args){
     int index = 0 ;
     int temp = 0 ;
     int totalSuc = 0 ;

     int numb[] = new int[4];//the first four numbers
     double num[][] = new double[36][3];//three numbers after calculating
     double total[] = new double[6];//the number after three steps of calculating



     double p[][] = new double[6][8];
     double q[][] = new double[3][7];



     //System.out.println(2465%108);
     //System.out.println(2465/108);

     System.out.println("\"a--b\"means\"b-a\"");
     System.out.println("\"a//b\"means\"b/a\"\n");
for(int i = 0 ; i < 4 ; i ++){
numb[i] = Integer.parseInt(args[i]);
}

       for(int i = 0; i < 3; i ++)//Get two of the four to calculate and then store the new number into the array p;
       for(int j = i + 1; j < 4 ; j ++,temp ++){
       p[temp][0] = numb[i] + numb[j];
       p[temp][1] = numb[i] - numb[j];
       p[temp][2] = numb[j] - numb[i];
       p[temp][3] = numb[i] * numb[j];
       if(numb[j] != 0)
       p[temp][4] = numb[i] / (double)numb[j];
       else
       p[temp][4] = 10000;
       if(numb[i] != 0)
       p[temp][5] = numb[j] / (double)numb[i];
       else
       p[temp][5] = 10000;



      switch(temp){
      case 0:p[temp][6] = numb[2]; p[temp][7] = numb[3];break;
      case 1:p[temp][6] = numb[1]; p[temp][7] = numb[3];break;
      case 2:p[temp][6] = numb[1]; p[temp][7] = numb[2];break;
      case 3:p[temp][6] = numb[0]; p[temp][7] = numb[3];break;
      case 4:p[temp][6] = numb[0]; p[temp][7] = numb[2];break;
      case 5:p[temp][6] = numb[0]; p[temp][7] = numb[1];
      }

      }

for(int k = 0,tem = 0; k < 6; k ++)//Get the possible three numbers and store into the array num[36][3] for calculating .
for(int l = 0; l < 6; l ++,tem ++){
num[tem][0] = p[k][l] ;
num[tem][1] = p[k][6] ;
num[tem][2] = p[k][7] ;

for(int t = 2,m = 0, n = 0,te = 0; t >= 0; t --,te ++){//Get two of the three to calculate and then store the new number into the array q;
   m = (t + 1)%3;
   n = (t + 2)%3;
   q[te][6] = num[tem][t];

   q[te][0] = num[tem][m] + num[tem][n];
   q[te][1] = num[tem][m] - num[tem][n];
   q[te][2] = num[tem][n] - num[tem][m];
   q[te][3] = num[tem][m] * num[tem][n];
   if(num[tem][n] != 0)
   q[te][4] = num[tem][m] / (double)num[tem][n];
   else
   q[te][4] = 10000 ;
   if(num[tem][m] != 0)
   q[te][5] = num[tem][n] / (double)num[tem][m];
   else
   q[te][5] = 10000 ;
   }

for(int u = 0; u < 3; u ++)
     for(int v = 0; v < 6; v ++){
     if(u == 2){//We must insure that the old value is in the left ,so the result string can be appended rightly.
     total[0] = q[u][6] + q[u][v];
     total[1] = q[u][6] - q[u][v];
     total[2] = q[u][v] - q[u][6];
     total[3] = q[u][v] * q[u][6];
     if(q[u][6] != 0)
     total[4] = q[u][6] / (double)q[u][v];
     else
     total[4] = 10000;
     if(q[u][v] != 0)
     total[5] = q[u][v] / (double)q[u][6];
     else
     total[5] = 10000;
     }
     else{
     total[0] = q[u][v] + q[u][6];
     total[1] = q[u][v] - q[u][6];
     total[2] = q[u][6] - q[u][v];
     total[3] = q[u][v] * q[u][6];
     if(q[u][6] != 0)
     total[4] = q[u][v] / (double)q[u][6];
     else
     total[4] = 10000;
     if(q[u][v] != 0)
     total[5] = q[u][6] / (double)q[u][v];
     else
     total[5] = 10000;
     }

     for(int s = 0 ; s < 6 ; s ++){
     if(total[s]>23.9999&&total[s]<24.0001){
     //System.out.println("24!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
     totalSuc ++ ;
     //print the expression
char x[] = new char[3];
int n0 = index ;
String expre = "" ;
String expre1 = "" ;
int n1 = index/108;//the first composition and its operator.
int n2 = index%108/6;//the second composition and its operator.
int n3 = index%6;//the last operator.

if(index == 3321){System.out.println(q[2][1] + " " +q[2][6]);}

switch(n1){

      case 0:expre += "((a+b)";x[1]='c';x[2]='d';break;
      case 1:expre += "((a-b)";x[1]='c';x[2]='d';break;
      case 2:expre += "((b-a)";x[1]='c';x[2]='d';break;
      case 3:expre += "((a*b)";x[1]='c';x[2]='d';break;
      case 4:expre += "((a/b)";x[1]='c';x[2]='d';break;
      case 5:expre += "((b/a)";x[1]='c';x[2]='d';break;
      case 6:expre += "((a+c)";x[1]='b';x[2]='d';break;
      case 7:expre += "((a-c)";x[1]='b';x[2]='d';break;
      case 8:expre += "((c-a)";x[1]='b';x[2]='d';break;
      case 9:expre += "((a*c)";x[1]='b';x[2]='d';break;
      case 10:expre += "((a/c)";x[1]='b';x[2]='d';break;
      case 11:expre += "((c/a)";x[1]='b';x[2]='d';break;
      case 12:expre += "((a+d)";x[1]='b';x[2]='c';break;
      case 13:expre += "((a-d)";x[1]='b';x[2]='c';break;
      case 14:expre += "((d-a)";x[1]='b';x[2]='c';break;
      case 15:expre += "((a*d)";x[1]='b';x[2]='c';break;
      case 16:expre += "((a/d)";x[1]='b';x[2]='c';break;
      case 17:expre += "((d/a)";x[1]='b';x[2]='c';break;
      case 18:expre += "((b+c)";x[1]='a';x[2]='d';break;
      case 19:expre += "((b-c)";x[1]='a';x[2]='d';break;
      case 20:expre += "((c-b)";x[1]='a';x[2]='d';break;
      case 21:expre += "((b*c)";x[1]='a';x[2]='d';break;
      case 22:expre += "((b/c)";x[1]='a';x[2]='d';break;
      case 23:expre += "((c/b)";x[1]='a';x[2]='d';break;
      case 24:expre += "((b+d)";x[1]='a';x[2]='c';break;
      case 25:expre += "((b-d)";x[1]='a';x[2]='c';break;
      case 26:expre += "((d-b)";x[1]='a';x[2]='c';break;
      case 27:expre += "((b*d)";x[1]='a';x[2]='c';break;
      case 28:expre += "((b/d)";x[1]='a';x[2]='c';break;
      case 29:expre += "((d/b)";x[1]='a';x[2]='c';break;
      case 30:expre += "((c+d)";x[1]='a';x[2]='b';break;
      case 31:expre += "((c-d)";x[1]='a';x[2]='b';break;
      case 32:expre += "((d-c)";x[1]='a';x[2]='b';break;
      case 33:expre += "((c*d)";x[1]='a';x[2]='b';break;
      case 34:expre += "((c/d)";x[1]='a';x[2]='b';break;
      case 35:expre += "((d/c)";x[1]='a';x[2]='b';
      }

      switch(n2){

      case 0:expre += "+" +x[1] +")";x[1]=x[2];break;//x[0] and x[1].
      case 1:expre += "-" +x[1] +")";x[1]=x[2];break;
      case 2:expre += "--" +x[1] +")";x[1]=x[2];break;
      case 3:expre += "*" +x[1] +")";x[1]=x[2];break;
      case 4:expre += "/" +x[1] +")";x[1]=x[2];break;
      case 5:expre += "//" +x[1] +")";x[1]=x[2];break;

      case 6:expre += "+" +x[2] +")";x[1]=x[1];break;//x[2] and x[0].
      case 7:expre += "--" +x[2] +")";x[1]=x[1];break;
      case 8:expre += "-" +x[2] +")";x[1]=x[1];break;
      case 9:expre += "*" +x[2] +")";x[1]=x[1];break;
      case 10:expre += "//" +x[2] +")";x[1]=x[1];break;
      case 11:expre += "/" +x[2] +")";x[1]=x[1];break;

      case 12:expre1 += x[1] + "+" + x[2] +"))";x[1]='(';break;//x[1] and x[2].
      case 13:expre1 += x[1] + "-" + x[2] +"))";x[1]='(';break;
      case 14:expre1 += x[1] + "--" + x[2] +"))";x[1]='(';break;
      case 15:expre1 += x[1] + "*" + x[2] +"))";x[1]='(';break;
      case 16:expre1 += x[1] + "/" + x[2] +"))";x[1]='(';break;
      case 17:expre1 += x[1] + "//" + x[2] +"))";x[1]='(';
      }

      switch(n3){

      case 0:expre += "+" +x[1] + expre1;break;
      case 1:expre += "-" +x[1] + expre1;break;
      case 2:expre += "--" +x[1] + expre1;break;
      case 3:expre += "*" +x[1] + expre1;break;
      case 4:expre += "/" +x[1] + expre1;break;
      case 5:expre += "//" +x[1] + expre1;
      }
      expre = expre.replace('a',(char)(numb[0] + 48));
      expre = expre.replace('b',(char)(numb[1] + 48));
      expre = expre.replace('c',(char)(numb[2] + 48));
      expre = expre.replace('d',(char)(numb[3] + 48));

      System.out.println(expre+"  ");
     }
     //System.out.println("total : " + total[s] + " index :" +"\n\n");


      index ++ ;
}

}

     }System.out.println("The number of total successful expressions is : " + totalSuc);
}

}

specialsoldier(雪地撒野) 的不好用
如：2 6 9 2

to 雪地撒野，你的程序也很好不过我运行的结果怎么只有
"a--b"means"b-a"
"a//b"means"b/a"
？？？
觉得好困惑呀

这个程序要求从命令行直接接受四个待算的数，java.lang.ArrayIndexOutOfBoundsException出现是由于你没有在运行时输满这四个数。
java Test24Point 1 2 3 4
看吧，有结果了大家好好试嘛，2 6 9 2 是可以的哦：
C:\金山词霸2005专业版\KPW2005\Common\kingsoft\Extract\Sound\hehe\t>java Test24Point 2 6 9 2
"a--b"means"b-a"
"a//b"means"b/a"((6/2)+9)*2
((2*9)-6)*2
((6/2)+9)*2
((9*2)-6)*2
The number of total successful expressions is : 4

一群大牛：一个比一个代码写得长，给大家个算法，本人觉得可以，不过可能会慢点
1，想办法把 +，-，*，/ 每次出现的时候随机化！
2，随机抽出4个数字进行运算，
3，跳出结果等于24的以下是部分代码
public int add(int a, int b){
  return a+b;
}
public int sub(int a, int b){
  return a-b;
}
public int mult(int a, int b){
  return a*b;
}
public int div(int a, int b){
  return a/b;
}public static void main(String [] args){
int result = (int)Math.random()*9);
ArrayList<String> resultlist=new ArrayList()<String>;
for(int i=0; i<4;i++){
String op=null;
  switch((int) Math.random*4){
  case:1 result = add(result,(int)Math.random()*9);op="+";
  case:2 result = sub(result,(int)Math.random()*9);op="-";
  case:3 result = mult(result,(int)Math.random()*9);op="*";
  case:4 result = div(result,(int)Math.random()*9);op="/";
  }
  resultlist.add(result.toString());
  resultlist.add(op.toString());
}
if(result=24){
resultlist.add("ok");
}
for(int j=0;j<result.length;j++){
String tmp=result.get(j);
if(tmp=="ok"){
for(int i=0;i<8;i++){
   System.out.println(result.get(j-(8-i));
    }
  }
}括号的情况可以依次类推；我可没有上机调试过啊，错了不要怪我！！！

呵呵，xdfbb(micwolf) ：
你的想法是蛮有灵性的，但你的程序是有问题的：1，第一次确实是可以任意两个值做四则运算，但第二次并不都是用上次算的结果和一新值做运算，也可能是另外两个新值先做运算，然后两个运算结果做四则，所以对于这个等式（2＋2）×（3＋3），我想你的程序是至死也算不出的。
2，你只能输出一个等式，这样适应面会比较窄，需求一变，就要做大手术了。我的程序确实比较混乱，也确实比较长（若不考虑输出，可以少100行呵呵）但应该没有逻辑方面的错误，恩，不过还得改进。我觉得大家应该互相鼓励，什么“一群大牛”之类的，那是日本人的秉性，那叫一欠cao。

specialsoldier(雪地撒野) 先生的代码是正确的，不过不好懂。
收藏大家去看看这个问题，解释清楚的另外加分，谢谢：http://community.csdn.net/Expert/topic/3942/3942532.xml?temp=.8107569

to 发恩，我只是懂一些c语言所以你的程序我就不怎么会改成java，真是不好意思

to 雪地撒野我已经知道了，我为什么出不来结果了，我用的调试工具是
eclipse,在dos下面调试应该可以出来结果的，又学到东西了

改造了一下雪地撒野的程序：
import java.util.ArrayList;public class Test24Point1{
final int TOTAL = 24;
final int NUMBER = 4;
final int OPNUMBER = 6;

public int numb[] = new int[NUMBER];//the first four numbers
ArrayList result = new ArrayList();

double p[][] = new double[NUMBER * (NUMBER - 1) / 2][OPNUMBER + NUMBER - 2];
double q[][] = new double[NUMBER - 1][OPNUMBER + (NUMBER - 1) - 2];

int index = 0;

public Test24Point1(int a, int b, int c, int d){
numb[0] = a;
numb[1] = b;
numb[2] = c;
numb[3] = d;
}

private void calculate1(){
int temp = 0 ;

       for(int i = 0; i < NUMBER - 1; i++)//Get two of the four to calculate and then store the new number into the array p;
       for(int j = i + 1; j < NUMBER ; j++, temp++){
       p[temp][0] = numb[i] + numb[j];
       p[temp][1] = numb[i] - numb[j];
       p[temp][2] = numb[j] - numb[i];
       p[temp][3] = numb[i] * numb[j];
       if(numb[j] != 0)
       p[temp][4] = numb[i] / (double)numb[j];
       else
       p[temp][4] = 10000;
       if(numb[i] != 0)
       p[temp][5] = numb[j] / (double)numb[i];
       else
       p[temp][5] = 10000;

      switch(temp){
      case 0:p[temp][6] = numb[2]; p[temp][7] = numb[3];break;
      case 1:p[temp][6] = numb[1]; p[temp][7] = numb[3];break;
      case 2:p[temp][6] = numb[1]; p[temp][7] = numb[2];break;
      case 3:p[temp][6] = numb[0]; p[temp][7] = numb[3];break;
      case 4:p[temp][6] = numb[0]; p[temp][7] = numb[2];break;
      case 5:p[temp][6] = numb[0]; p[temp][7] = numb[1];
      }

      }
}

private void calculate2(){
double num[][] = new double[OPNUMBER * NUMBER * (NUMBER - 1) / 2][NUMBER - 1];//three numbers after calculating

for(int k = 0,tem = 0; k < NUMBER * (NUMBER - 1) / 2; k++)//Get the possible three numbers and store into the array num[][] for calculating .
for(int l = 0; l < OPNUMBER; l++, tem++){
num[tem][0] = p[k][l] ;
num[tem][1] = p[k][6] ;
num[tem][2] = p[k][7] ;

for(int t = 2, m = 0, n = 0, te = 0; t >= 0; t--, te++){//Get two of the three to calculate and then store the new number into the array q;
   m = (t + 1)%3;
   n = (t + 2)%3;
   q[te][6] = num[tem][t];

   q[te][0] = num[tem][m] + num[tem][n];
   q[te][1] = num[tem][m] - num[tem][n];
   q[te][2] = num[tem][n] - num[tem][m];
   q[te][3] = num[tem][m] * num[tem][n];
   if(num[tem][n] != 0)
   q[te][4] = num[tem][m] / (double)num[tem][n];
   else
   q[te][4] = 10000 ;
   if(num[tem][m] != 0)
   q[te][5] = num[tem][n] / (double)num[tem][m];
   else
   q[te][5] = 10000 ;
   }
calculate3();
     }
}

private void calculate3(){
double total[] = new double[OPNUMBER];//the number after three steps of calculating

for(int u = 0; u < 3; u++)
     for(int v = 0; v < OPNUMBER; v++){
     if(u == 2){//We must insure that the old value is at the left ,so the result string can be appended rightly.
     total[0] = q[u][6] + q[u][v];
     total[1] = q[u][6] - q[u][v];
     total[2] = q[u][v] - q[u][6];
     total[3] = q[u][v] * q[u][6];
     if(q[u][6] != 0)
     total[4] = q[u][6] / (double)q[u][v];
     else
     total[4] = 10000;
     if(q[u][v] != 0)
     total[5] = q[u][v] / (double)q[u][6];
     else
     total[5] = 10000;
     }
     else{
     total[0] = q[u][v] + q[u][6];
     total[1] = q[u][v] - q[u][6];
     total[2] = q[u][6] - q[u][v];
     total[3] = q[u][v] * q[u][6];
     if(q[u][6] != 0)
     total[4] = q[u][v] / (double)q[u][6];
     else
     total[4] = 10000;
     if(q[u][v] != 0)
     total[5] = q[u][6] / (double)q[u][v];
     else
     total[5] = 10000;
     }

     for(int s = 0; s < OPNUMBER; s++){
     if(total[s] > TOTAL - .0001 && total[s] < TOTAL + .0001){
     //print the expression
char x[] = new char[3];
int n0 = index ;
String expre = "" ;
String expre1 = "" ;
int n1 = index / (OPNUMBER * NUMBER * (NUMBER - 1) / 2 * (NUMBER - 1));//the first composition and its operator.
int n2 = index % (OPNUMBER * NUMBER * (NUMBER - 1) / 2 * (NUMBER - 1)) / OPNUMBER;//the second composition and its operator.
int n3 = index % OPNUMBER;//the last operator. switch(n1){
      case 0:expre += "((a+b)";x[1]='c';x[2]='d';break;
      case 1:expre += "((a-b)";x[1]='c';x[2]='d';break;
      case 2:expre += "((b-a)";x[1]='c';x[2]='d';break;
      case 3:expre += "((a*b)";x[1]='c';x[2]='d';break;
      case 4:expre += "((a/b)";x[1]='c';x[2]='d';break;
      case 5:expre += "((b/a)";x[1]='c';x[2]='d';break;
      case 6:expre += "((a+c)";x[1]='b';x[2]='d';break;
      case 7:expre += "((a-c)";x[1]='b';x[2]='d';break;
      case 8:expre += "((c-a)";x[1]='b';x[2]='d';break;
      case 9:expre += "((a*c)";x[1]='b';x[2]='d';break;
      case 10:expre += "((a/c)";x[1]='b';x[2]='d';break;
      case 11:expre += "((c/a)";x[1]='b';x[2]='d';break;
      case 12:expre += "((a+d)";x[1]='b';x[2]='c';break;
      case 13:expre += "((a-d)";x[1]='b';x[2]='c';break;
      case 14:expre += "((d-a)";x[1]='b';x[2]='c';break;
      case 15:expre += "((a*d)";x[1]='b';x[2]='c';break;
      case 16:expre += "((a/d)";x[1]='b';x[2]='c';break;
      case 17:expre += "((d/a)";x[1]='b';x[2]='c';break;
      case 18:expre += "((b+c)";x[1]='a';x[2]='d';break;
      case 19:expre += "((b-c)";x[1]='a';x[2]='d';break;
      case 20:expre += "((c-b)";x[1]='a';x[2]='d';break;
      case 21:expre += "((b*c)";x[1]='a';x[2]='d';break;
      case 22:expre += "((b/c)";x[1]='a';x[2]='d';break;
      case 23:expre += "((c/b)";x[1]='a';x[2]='d';break;
      case 24:expre += "((b+d)";x[1]='a';x[2]='c';break;
      case 25:expre += "((b-d)";x[1]='a';x[2]='c';break;
      case 26:expre += "((d-b)";x[1]='a';x[2]='c';break;
      case 27:expre += "((b*d)";x[1]='a';x[2]='c';break;
      case 28:expre += "((b/d)";x[1]='a';x[2]='c';break;
      case 29:expre += "((d/b)";x[1]='a';x[2]='c';break;
      case 30:expre += "((c+d)";x[1]='a';x[2]='b';break;
      case 31:expre += "((c-d)";x[1]='a';x[2]='b';break;
      case 32:expre += "((d-c)";x[1]='a';x[2]='b';break;
      case 33:expre += "((c*d)";x[1]='a';x[2]='b';break;
      case 34:expre += "((c/d)";x[1]='a';x[2]='b';break;
      case 35:expre += "((d/c)";x[1]='a';x[2]='b';
      }

      switch(n2){

      case 0:expre += "+" +x[1] +")";x[1]=x[2];break;//x[0] and x[1].
      case 1:expre += "-" +x[1] +")";x[1]=x[2];break;
      case 2:expre = convertMinus(expre, x[1]);x[1]=x[2];break;
      case 3:expre += "*" +x[1] +")";x[1]=x[2];break;
      case 4:expre += "/" +x[1] +")";x[1]=x[2];break;
      case 5:expre = convertDivide(expre, x[1]);x[1]=x[2];break;

      case 6:expre += "+" +x[2] +")";x[1]=x[1];break;//x[2] and x[0].
      case 7:expre = convertMinus(expre, x[2]);x[1]=x[1];break;
      case 8:expre += "-" +x[2] +")";x[1]=x[1];break;
      case 9:expre += "*" +x[2] +")";x[1]=x[1];break;
      case 10:expre = convertDivide(expre, x[2]);x[1]=x[1];break;
      case 11:expre += "/" +x[2] +")";x[1]=x[1];break;

      case 12:expre1 += x[1] + "+" + x[2] +"))";x[1]='(';break;//x[1] and x[2].
      case 13:expre1 += x[1] + "-" + x[2] +"))";x[1]='(';break;
      case 14:expre1 += x[2] + "-" + x[1] +"))";x[1]='(';break;
      case 15:expre1 += x[1] + "*" + x[2] +"))";x[1]='(';break;
      case 16:expre1 += x[1] + "/" + x[2] +"))";x[1]='(';break;
      case 17:expre1 += x[2] + "/" + x[1] +"))";x[1]='(';
      }

      switch(n3){
      case 0:expre += "+" +x[1] + expre1;break;
      case 1:expre += "-" +x[1] + expre1;break;
      case 2:expre = convertMinus(expre, x[1], expre1);break;
      case 3:expre += "*" +x[1] + expre1;break;
      case 4:expre += "/" +x[1] + expre1;break;
      case 5:expre = convertDivide(expre, x[1], expre1);
      }
      expre = expre.replace('a',(char)(numb[0] + 48));
      expre = expre.replace('b',(char)(numb[1] + 48));
      expre = expre.replace('c',(char)(numb[2] + 48));
      expre = expre.replace('d',(char)(numb[3] + 48));

      if(!result.contains(expre)){
      result.add(expre);
      }
     }
      index++ ;
}
}
}

private String convertMinus(String exp, char x){
exp = "(" + x + "-" + exp.substring(1) + ")";
return exp;
}

private String convertDivide(String exp, char x){
exp = "(" + x + "/" + exp.substring(1) + ")";
return exp;
} private String convertMinus(String exp, char x, String exp1){
int l = exp1.length();
if (l ==0){
exp = "(" + x + "-" + exp + ")";
}
else{
exp = "(" + x + exp1.substring(0, l -1 ) + "-" + exp.substring(1) + ")";
}
return exp;
}

private String convertDivide(String exp, char x, String exp1){
int l = exp1.length();
if (l ==0){
exp = "(" + x + "/" + exp + ")";
}
else{
exp = "(" + x + exp1.substring(0, l -1 ) + "/" + exp.substring(1) + ")";
}
return exp;
}

private void printResult(){
System.out.println("\r\n" + numb[0] + " " + numb[1] + " " + numb[2] + " " + numb[3] + ":");
System.out.println("The number of total successful expressions is : " + result.size());
        for( short i = 0; i < result.size(); i++ )
            System.out.println(result.get(i));
}

    public static void main(String[] args){
     Test24Point1 t24 = new Test24Point1(1, 6, 8, 6);
     t24.calculate1();
     t24.calculate2();
     t24.printResult();

     t24 = new Test24Point1(4, 1, 3, 8);
     t24.calculate1();
     t24.calculate2();
     t24.printResult();

     t24 = new Test24Point1(4, 4, 9, 6);
     t24.calculate1();
     t24.calculate2();
     t24.printResult();     t24 = new Test24Point1(2, 2, 8, 9);
     t24.calculate1();
     t24.calculate2();
     t24.printResult();

int a = (int)(9 * Math.random() + 1);
int b = (int)(9 * Math.random() + 1);
int c = (int)(9 * Math.random() + 1);
int d = (int)(9 * Math.random() + 1);
     t24 = new Test24Point1(a, b, c, d);
     t24.calculate1();
     t24.calculate2();
     t24.printResult();
}
}
如果再改一下用递归，我想可以实现任意个数，运算后的某值的算法。

我也来凑凑热闹
public  class TwentyFour {
  static short num[] = new short[4];
  static char op[] = new char[3];
  public static void  main(String args[]){
     short a[] = new short[4];
     a[0] = Short.parseShort( args[0] );
     a[1] = Short.parseShort( args[1] );
     a[2] = Short.parseShort( args[2] );
     a[3] = Short.parseShort( args[3] );


     for(int i = 0 ; i < 4 ; i ++){
       for(int j = 0 ; j < 4 ; j ++){
         if(j == i) continue;
         for(int k = 0 ; k < 4 ; k ++){
           if(k == i || k == j) continue;
           for(int p = 0 ; p < 4 ; p ++){
             if(p == k || p == j || p==i ) continue;
             num[0] = a[i];
             num[1] = a[j];
             num[2] = a[k];
             num[3] = a[p];
             next((int)num[0] ,0);
           }
         }
       }
     }
  }
     static void next(int current,  int count){
        if( count >= 3){
           if(current == 24){
              write();
           }
           return;
        }

        int n = num[count + 1];
        op[count] = '*';
        next(current * n, count + 1);
        if( (n != 0) && (current > n) && ((current % n) == 0) ){
           op[count] = '/';
           next(current / n , count + 1);
        }
        op[count] = '+';
        next(current + n, count + 1);
        op[count] = '-';
        next(current - n , count + 1);
     }

     static void write(){
       System.out.println("((" + num[0] + op[0] + num[1] + ")" + op[1] + num[2] + ")"+ op[2] + num[3]  );
     }
}

public  class TwentyFour {
  static short num[] = new short[4];
  static char op[] = new char[3];
  public static void  main(String args[]){
     short a[] = new short[4];
     a[0] = Short.parseShort( args[0] );
     a[1] = Short.parseShort( args[1] );
     a[2] = Short.parseShort( args[2] );
     a[3] = Short.parseShort( args[3] );


     for(int i = 0 ; i < 4 ; i ++){
       for(int j = 0 ; j < 4 ; j ++){
         if(j == i) continue;
         for(int k = 0 ; k < 4 ; k ++){
           if(k == i || k == j) continue;
           for(int p = 0 ; p < 4 ; p ++){
             if(p == k || p == j || p==i ) continue;
             num[0] = a[i];
             num[1] = a[j];
             num[2] = a[k];
             num[3] = a[p];
             next((int)num[0] ,0);
             if( (num[0] + num[1] ) * (num[2] + num[3] ) == 24)
               writeTwo(num[0],'+',num[1],'*',num[2],'+',num[3]);
             if( (num[0] - num[1] ) * (num[2] + num[3] ) == 24)
               writeTwo(num[0],'-',num[1],'*',num[2],'+',num[3]);
           }
         }
       }
     }
  }
     static void next(int current,  int count){
        if( count >= 3){
           if(current == 24){
              write();
           }
           return;
        }

        int n = num[count + 1];
        op[count] = '*';
        next(current * n, count + 1);
        if( (n != 0) && (current > n) && ((current % n) == 0) ){
           op[count] = '/';
           next(current / n , count + 1);
        }
        op[count] = '+';
        next(current + n, count + 1);
        op[count] = '-';
        next(current - n , count + 1);
     }

     static void writeTwo(int num1, char op1,int num2 ,char op2,int num3 ,char op3,int num4){
       System.out.println("(" + num1 + op1 + num2 + ")" + op2 + "(" + num3 + op3 + num4 + ")");
     }

     static void write(){
       System.out.println("((" + num[0] + op[0] + num[1] + ")" + op[1] + num[2] + ")"+ op[2] + num[3]  );
     }
}现在好了  就是效率低了点  可扩展性也不好

yulin001122() :
很简洁，效率没问题，但是逻辑有点漏洞，你第一个程序根本没考虑(a@b)@(c@d)这类的情况(@暂表示四则运算之一)如：(2+2)*(3+3),所以在第二个程序里用if判断后调用writeTwo（）来弥补。但还有一种等式类型你没有判断：a@(b@c@d),如6/(1-3/4),8/(3-8/3)，需要再添几个if判断然后调writeOthers（）吧。

或者再自定义两个运算符吧，a--b表示b-a,a//b表示b/a，就不用增加那么多判断了，不过就变成六则运算了，呵呵，能不能这么说不知道。

调试易

0-9数字随意抽出4个数字用java编程怎么能够用四则运算还有括号得到24

解决方案 »