x24.cpp

计算24点的C++源码

#include<iostream>
#include<string>

using namespace std;

double number[4];
string expression[4];

bool Search(int n)
{
	if(n==1)
	{
		if(number[0]==24)
		{
			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];
			
			number[i]=a+b;
			expression[i]="(" + expa + "+" + expb + ")";
			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;
			}
			
			if(a!=0)
			{
				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;
}

int main()
{
	for(int i=0;i<4;i++)
	{
		char buffer[20];
		int x;
		cin>>x;
		number[i]=x;
		itoa(x,buffer,10);
		expression[i]=buffer;
	}
	
	if(Search(4))
	{
		cout<<"Success!"<<endl;
	}
	else
	{
		cout<<"Fail!"<<endl;
	}

	return 0;
}