题目

https://www.luogu.com.cn/problem/P4718

思路

真的是阴间卡常模板题
blog

代码

#include<bits/stdc++.h>
#define ll long long
#define ld long double
#define ull unsigned long long
using namespace std;
int T;
ll ans,n;
inline ll mul(ll x,ll y,ll p)
{
	ll yjy=(ld)x/p*y;
	ll aii=(ull)x*y-(ull)yjy*p;
	if(aii<0) aii+=p; if(aii>=p) aii-=p;
	return aii;
}
inline ll power(ll x,ll t,ll mod)
{
	ll b=1;
	while(t)
	{
		if(t&1) b=mul(b,x,mod); x=mul(x,x,mod); t>>=1;
	}
	return b;
}
inline ll gcd(ll x,ll y)
{
	return y==0?x:gcd(y,x%y);
}
bool miller(ll n,int yjy)
{
	if(n==2||n==3) return 1;
	if(n%2==0||n==1) return 0;
	ll d=n-1,s=0;
	while(!(d&1)) s++,d>>=1;
	while(yjy--)
	{
		ll a=rand()%(n-3)+2,x=power(a,d,n),y=0;
		for(int X=1; X<=s; X++)
		{
			y=mul(x,x,n);
			if(y==1&&x!=1&&x!=n-1) 
				return 0;
			x=y;
		}
		if(y!=1) 
			return 0;
	}
	return 1;
}
ll pollard(ll n)
{
	ll x=rand()%(n-1)+1,y=x,i=1,k=2,c=rand()%n,val=1;
	while(1)
	{
		i++;
		x=(mul(x,x,n)+c)%n;
		val=mul(val,abs(y-x),n);
		if(y==x) return n;
		if(i==k||i%63==0||i%127==0)
		{
			ll d=gcd(n,val);
			if(1<d&&d<n) return d;
			if(i==k) y=x,k<<=1;
		}
	}
}
void find(ll n)
{
	if(n==1) return;
	if(ans>=n) return;
	if(miller(n,20))
	{
		ans=max(ans,n); return;
	}
	ll p=n;
	while(p==n) 
		p=pollard(p);
	find(p); find(n/p);
}
int main()
{
	srand(time(NULL));
	scanf("%d",&T);
	while(T--)
	{
		ans=0;
		scanf("%lld",&n);
		find(n);
		if(ans==n) printf("Prime\n");
		else printf("%lld\n",ans);
	}
}