poj 3421 X-factor Chains(分解质因数+组合数学)

幂和的阶乘/幂阶乘的和

#include<stdio.h>
#include<string.h>
#define ll long long
ll j[25];
void ini()
{
	j[1]=1;
	for(ll i=2;i<=20;i++)
		j[i]=j[i-1]*i;
}
int main()
{
	ini();
	ll n;
	while(scanf("%lld",&n)!=EOF)
	{
		int ans=0;
		ll b=1;
		for(ll i=2;i*i<=n;i++)
			if(n%i==0)
			{
				int cnt=0;
				while(n%i==0)
				{
					cnt++;
					n/=i;
				}
				ans+=cnt;
				b*=j[cnt];
			}
		if(n>1) ans+=1;
		printf("%d %lld\n",ans,j[ans]/b);
	}
	return 0;
}