zoj 2562 More Divisors

題解：求出n以內的最大的反素數。

#include 
#include 
using namespace std;
typedef unsigned long long LL;

LL p[]={2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53};
LL ans,sum;
LL N;

void dfs(LL i,LL x,LL n)
{
    if(n>sum||(n==sum&&ans>x)) sum=n,ans=x;
    for(int k=1;k<=63;k++)
    {
        if(x*p[i]>N) break;
        dfs(i+1,x*=p[i],n*(k+1));
    }
}


int main()
{
    while(cin>>N)
    {
        ans=1e18;
        sum=1;
        dfs(0,1,1);
       cout<