24点游戏

// code.cpp : 定义控制台应用程序的入口点。
// editor: Visual C++ 2010 Ultimate
// system: win7 x32
// create: 2013-08-02 10:46AM
// author: starfish(海星)
// remark: 转载自大神的文章片段，提交pongo需修改

#include "stdafx.h"
#include <iostream>
#include <string>
#include <cmath>
using namespace std;

const double PRECISION = 1E-6;
const int COUNT_OF_NUMBER = 4;
const int NUMBER_TO_CAL = 24;

double number[COUNT_OF_NUMBER];
string expression[COUNT_OF_NUMBER];

bool Search(int n);

int _tmain(int argc, _TCHAR* argv[])
{
for(int i=0;i<COUNT_OF_NUMBER; i++){
char buffer[20];
int x;
cin>>x;
number[i] = x;
itoa(x, buffer, 10);
expression[i] = buffer;
}

if(Search(COUNT_OF_NUMBER)){
cout<< "SUCCESS" <<endl;
} else {
cout<< "FAILURE" <<endl;
}
system("pause");
return 0;
}

bool Search(int n)
{
if(n==1){
if(fabs(number[0]-NUMBER_TO_CAL)<PRECISION){
cout<<expression[0]<<endl;
return true;
} else {
return false;
}
}
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(Search(n-1)) return true;

expression[i] = '(' + expa + '-' + expb + ')';
number[i] = a - b;
if(Search(n-1)) return true;

expression[i] = '(' + expb + '-' + expa + ')';
number[i] = b - a;
if(Search(n-1)) return true;

expression[i] = '(' + expa + '*' + expb + ')';
number[i] = a * b;
if(Search(n-1)) return true;

if(b!=0){
expression[i] = '(' + expa + '/' + expb + ')';
number[i] = a / b;
if(Search(n-1)) return true;
//-- 算分数24点 jkj --//
expression[i] = '(' + expb + '/' + expa + ')';
number[i] = b / a;
if(Search(n-1)) return true;
}

number[i] = a;
number[j] = b;
expression[i] = expa;
expression[j] = expb;

}
}
return false;
}