快算24点，POJ(3983)

题目链接：http://poj.org/problem?id=3983

中文题，就不解释题意了。

类似之前的一篇博客，这里也不上解释了，直接上代码吧。

#include <iostream>
#include <stdio.h>
#include <string>
using namespace std;

char op[4]={'+','-','*','/'};

double calc(double a,int opnum,double b)
{
    switch(op[opnum])
    {
        case '+':
            return a+b;
            break;
        case '-':
            return a-b;
            break;
        case '*':
            return a*b;
            break;
        case '/':
            return a/b;
            break;
    }
    
}

bool calculator(int i, int j, int k, double a, double b, double c, double d)
{
    if (calc(calc(a, i, b),j,calc(c, k, d)) - 24.0 == 0)
    {
        printf("(%.0lf%c%.0lf)%c(%.0lf%c%.0lf)
",a, op[i], b, op[j], c, op[k], d);
        return 1;
    }
    if (calc(calc(calc(a, i, b), j, c), k, d) - 24.0 == 0)
    {
        printf("((%.0lf%c%.0lf)%c%.0lf)%c%.0lf)
",a, op[i], b, op[j], c, op[k], d);
        return 1;
    }
    if (calc(calc(a, i, calc(b, j, c)), k, d) - 24.0 == 0)
    {
        printf("(%.0lf%c(%.0lf%c%.0lf))%c%.0lf)
",a, op[i], b, op[j], c, op[k], d);
        return 1;
    }
    if (calc(a, i, calc(calc(b, j, c), k, d)) - 24.0 == 0)
    {
        printf("%.0lf%c((%.0lf%c%.0lf)%c%.0lf)
",a, op[i], b, op[j], c, op[k], d);
        return 1;
    }
    if (calc(a, i, calc(b, j, calc(c, k, d))) == 24.0)
    {
        printf("%.0lf%c(%.0lf%c(%.0lf%c%.0lf))
",a, op[i], b, op[j], c, op[k], d);
        return 1;
    }
    return 0;
}


int main()
{
    double a,b,c,d;
    while (scanf("%lf %lf %lf %lf", &a, &b, &c, &d) != EOF)
    {
        for (int i = 0; i < 4; i++)
        {
            for (int j = 0; j < 4; j++)
            {
                for (int k = 0; k < 4; k++)
                {
                    if (calculator(i,j,k,a,b,c,d)==1)
                        goto over;
                }
            }
        }

        over:continue;
    }

    return 0;
}