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;
}