求24问题？

sun1889 2005-10-20 01:26:02

运用加减乘除求出结果等于24。[C语言]

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tanghui0512 2005-10-22

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有一个人家写的，自己看不大懂
#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)
{
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;
}
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;
}
void main()
{
while(1)
{
cout<<"Input 4 Numbers:";
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 << "Fail." << endl;
}
cout<<endl;
}

}

bombwang 2005-10-22

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学习

appleyy 2005-10-21

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完了，，我怎么向外送分啊。。。我给出的问题点数是20。

不知道怎么向外送，穷的就剩下点数了。哈哈！
-------------------------
管理

koil 2005-10-21

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楼上星哥的，看不懂解释下

qhfu 2005-10-21

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#include <iostream>
#include <string>
#include <cmath>

using namespace std;

const double PRECISION = 0.00001;

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

bool Search(int n)
{
if (n == 1)
{
if (fabs(number[0] - 24) < 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;
}

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()
{
cout <<"Please input four numbers:" <<endl;

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;
}
system("pause");
return 0;
}

sun1889 2005-10-21