湖南多校对抗赛（2015.05.03）Problem A: Twenty-four point

给四个数 问能不能算出24点。。。我的方法比较烂。。。920ms 差点TLE。应该有更好的方法。

 

#include<stdio.h>
#include<string.h>
#include<math.h>
#include<algorithm>
using namespace std;
double a[5], ff[5], n;
double rt[30][5], yy[5];
int sum;
double get(double x, double y, int fu)
{
    if (fu == 1) return x + y;
    if (fu == 2) return x - y;
    if (fu == 3) return x * y;
    if (fu == 4) return x / y;
}
void dfs(int tot)
{
    int ii;
    if (tot == 4)
    {
        rt[sum][1] = yy[0];
        rt[sum][2] = yy[1];
        rt[sum][3] = yy[2];
        rt[sum][4] = yy[3];
        sum++;
        return;
    }
    for (ii = 0; ii < 4; ii++)
    {
        if (ff[ii] == 0)
        {
            ff[ii] = 1;
            yy[tot] = a[ii];
            dfs(tot + 1);
            ff[ii] = 0;
        }
    }
}
int main()
{
    while (~scanf("%lf%lf%lf%lf", &a[0], &a[1], &a[2], &a[3]))
    {
        memset(ff, 0, sizeof(ff));
        sum = 1; dfs(0); int i, j, k, g;
        int ans = 0;
        double linshi1 = 0, linshi2 = 0, linshi3 = 0;
        double z, x, c, v;
        for (i = 1; i <= 24; i++)
        {
            for (g = 1; g <= 4; g++)
            {
                for (k = 1; k <= 4; k++)
                {
                    for (j = 1; j <= 4; j++)
                    {
                         
                        z = rt[i][1]; x = rt[i][2]; c = rt[i][3]; v = rt[i][4];
                        linshi1 = get(z, x, g);
                        linshi2 = get(linshi1, c, k);
                        linshi3 = get(linshi2, v, j);
                        if (fabs(linshi3 - 24)<0.0000001){ ans = 1; break; }
 
                         
                        linshi1 = get(z, x, g);
                        linshi2 = get(c, v, j);
                        linshi3 = get(linshi1, linshi2, k);
                        if (fabs(linshi3 - 24)<0.0000001){ ans = 1; break; }
 
                         
                        linshi1 = get(x, c, k);
                        linshi2 = get(z, linshi1, g);
                        linshi3 = get(linshi2, v, j);
                        if (fabs(linshi3 - 24)<0.0000001){ ans = 1; break; }
 
                         
                        linshi1 = get(x, c, k);
                        linshi2 = get(linshi1, v, j);
                        linshi3 = get(z, linshi2, g);
                        if (fabs(linshi3 - 24)<0.0000001){ ans = 1; break; }
 
                         
                        linshi1 = get(c, v, j);
                        linshi2 = get(z, x, g);
                        linshi3 = get(linshi1, linshi2, k);
                        if (fabs(linshi3 - 24)<0.0000001){ ans = 1; break; }
 
                         
                        linshi1 = get(c, v, j);
                        linshi2 = get(x, linshi1, k);
                        linshi3 = get(z, linshi2, g);
                        if (fabs(linshi3 - 24)<0.0000001){ ans = 1; break; }
 
                    }
                    if (ans) break;
                }
                if (ans) break;
            }
            if (ans) break;
        }
        if (ans == 1)printf("Yes\n");
        else printf("No\n");
    }
    return 0;
}