简单24点游戏

#include<iostream>  
#include<string>  
#include<cmath>  
using namespace std;  
const double PRECISION = 1E-6;  
const int COUNT = 4;  
const int RESULT = 24;  
double number[COUNT];     
string expression[COUNT];    //保存表达式  


bool Test(int n)  
{  


//递归结束  
    if (n == 1)  
    {  
if (fabs(number[0] - RESULT) < PRECISION)  
{  
cout << expression[0] << endl;  
return true;  
}  
else  
return false;  
}  


//递归过程  


for (int i = 0; i < n; i++)  
{  


for (int j = i + 1; j < n; j++)  
{  
double a, b;  
string expa, expb;  
a = number[i];  
b = number[j];  
number[j] = number[n - 1];  
expa = expression[i];  
expb = expression[j];  
expression[j] = expression[n - 1];  
expression[i] = '(' + expa + '+' + expb + ')';  
number[i] = a + b;  
if (Test(n - 1))  
return true;  
//减号有两种情况,a-b与b-a  
expression[i] = '(' + expa + '-' + expb + ')';  
number[i] = a - b;  
if (Test(n - 1))  
return true;  
expression[i] = '(' + expb + '-' + expa + ')';  
number[i] = b - a;  
if (Test(n - 1))  
return true;  
expression[i] = '(' + expa + '*' + expb + ')';  
number[i] = a * b;  
if (Test(n - 1))  
return true;  
//除法也有两种情况,a/b与b/a  
if (b != 0)  
{  
expression[i] = '(' + expa + '/' + expb + ')';  
number[i] = a / b;  
if (Test(n - 1))  
return true;  
}  
if (a != 0)  
{  
expression[i] = '(' + expb + '/' + expa + ')';  
number[i] = b / a;  
if (Test(n - 1))  
return true;  
}  
//恢复数组  
number[i] = a;  
number[j] = b;  
expression[i] = expa;  
expression[j] = expb;  
}  
}  
return false;  
}  

int main(void)  
{  

    for (int i = 0; i < COUNT; i++)  
    {     
char buffer[20];  
int x; 
cout<<"请输入4位数字:"<<endl;
cin >> x;  
number[i] = x;  
itoa(x, buffer, 10);  
expression[i] = buffer;  
}  


if (Test(COUNT))  
cout << "Success" << endl;  
else  
cout << "Fail" << endl;  
system("pause");  
return 0;  
}