UVA-10976 - Fractions Again?!

我真给这个题跪了  精度控制竟然到1e-17才给过，从discuss上找了很多数据，考虑极端情况10000时就好了，这是个边界，到现在弄不懂加0.5干嘛的，用的暴利枚举，以下是AC代码：

#include
#include
#include
#include
#include
using namespace std;
int t1[20010],t2[20010];
int main()
{
    freopen("out.txt","w",stdout);
    int k,n = 0;
    while(cin>>k)
    {
        n = 0;
        memset(t1,0,sizeof(t1));
        memset(t2,0,sizeof(t2));
        int x,y,kase = 0;
        for(y = 1;y <= 2*k;y++)
            if(1.0/k - 1.0/y > 1e-17)
            {
                double temp = 1.0/k - 1.0/y;
                int temp2 = (1.0/temp+0.5);
                if(1.0/temp2 + 1.0/y - 1.0/k < 1e-17&&1.0/temp2 + 1.0/y - 1.0/k > -1e-17)
                {
                    kase++;
                    t1[n] = temp2;
                    t2[n++] = y;
                }
            }
        printf("%d\n",kase);
        for(int i = 0;;i++)
        {
            if(!t1[i]&&!t2[i])
                break;
            printf("1/%d = 1/%d + 1/%d\n" ,k,t1[i],t2[i]);
        }
    }
    return 0;
}