下面是我的 $75pts$ 代码，四个点超时。

#include <bits/stdc++.h>
#define ull unsigned long long
#define ll long long
#define ld long double
using namespace std;
int t;
ll ksc (ll x, ll y, ll p) 
{
	return ((ull) x * y - (ull) ((ld) x / p * y) * p + p) % p;
}
ll gcd (ll a, ll b) 
{
	if (a < b) swap (a, b);
	if (b == 0) return a;
	else return gcd (b, a % b);
}
ll ksm (ll a, ll b, ll mod) 
{
	if (b == 0) return 1;
	if (b == 1) return a % mod;
	ll mid =  ksm (a, b / 2, mod);
	mid = ksc (mid, mid, mod);
	if (b % 2 == 0) return mid;
	else return ksc (mid, a, mod);
}
ll test[11] = {0, 2, 3, 5, 7, 11, 13, 17, 19, 23, 29};
bool Miller_Robin (ll n) 
{
	if (n < 2) return false;
	for (int i = 1; i <= 10; i++) 
	{
		ll a = test[i];
		if (n == a) return true;
		if (ksm (a, n - 1, n) != 1) return false;
		ll t = n - 1;
		while (! (t & 1) && t != 0) 
		{
			t >>= 1;
			ll cur = ksm (a, t, n);
			if (cur != n - 1 && cur != 1) return false;
			if (cur == n - 1) break;
		}
	}
	return true;
} 
ll Pollard_Rho (ll n) 
{
	if (n == 4) return 2;
	srand (time (0));
	ll a = rand () % (n - 1) + 1, 
	   c = rand () % (n - 3) + 3;
	ll b = a;
	a = (ksc (a, a, n) + c) % n;
	b = (ksc (b, b, n) + c) % n,
	b = (ksc (b, b, n) + c) % n;
	for (int lim = 1; a != b; lim = min (lim << 1, 128)) 
	{
		ll cnt = 1;
		for (int stp = 1; stp <= lim; stp++) 
		{
			ll tmp = ksc (cnt, abs (b - a), n);
			if (!tmp) break;
			cnt = tmp;
			a = (ksc (a, a, n) + c) % n;
			b = (ksc (b, b, n) + c) % n,
			b = (ksc (b, b, n) + c) % n;
		}
		ll d = gcd (cnt, n);
		if (d != 1) return d;
	}
	return n;
}
ll ans = 0;
void Get_Maxfactor (ll n) 
{
	ll d = Pollard_Rho (n), di;
	while (d == n) d = Pollard_Rho (n);
	di = n / d;
	if (Miller_Robin (d)) ans = max (ans, d);
	else Get_Maxfactor (d);
	if (Miller_Robin (di)) ans = max (ans, di);
	else Get_Maxfactor (di);
	return;
}
int main ()
{
	scanf ("%d", &t);
	while (t--) 
	{
		ll x;
		scanf ("%lld", &x);
		if (Miller_Robin (x)) 
			printf ("Prime\n");
		else 
		{
			ans = 0;
			Get_Maxfactor (x);
			printf ("%lld\n", ans);
		}
			
	}
	return 0;
}

下面是我的 AC 代码，与上代码的区别是删除了 srand(time(0)) 这个语句。

#include <bits/stdc++.h>
#define ull unsigned long long
#define ll long long
#define ld long double
using namespace std;
int t;
ll ksc (ll x, ll y, ll p) 
{
	return ((ull) x * y - (ull) ((ld) x / p * y) * p + p) % p;
}
ll gcd (ll a, ll b) 
{
	if (a < b) swap (a, b);
	if (b == 0) return a;
	else return gcd (b, a % b);
}
ll ksm (ll a, ll b, ll mod) 
{
	if (b == 0) return 1;
	if (b == 1) return a % mod;
	ll mid =  ksm (a, b / 2, mod);
	mid = ksc (mid, mid, mod);
	if (b % 2 == 0) return mid;
	else return ksc (mid, a, mod);
}
ll test[11] = {0, 2, 3, 5, 7, 11, 13, 17, 19, 23, 29};
bool Miller_Robin (ll n) 
{
	if (n < 2) return false;
	for (int i = 1; i <= 10; i++) 
	{
		ll a = test[i];
		if (n == a) return true;
		if (ksm (a, n - 1, n) != 1) return false;
		ll t = n - 1;
		while (! (t & 1) && t != 0) 
		{
			t >>= 1;
			ll cur = ksm (a, t, n);
			if (cur != n - 1 && cur != 1) return false;
			if (cur == n - 1) break;
		}
	}
	return true;
} 
ll Pollard_Rho (ll n) 
{
	if (n == 4) return 2;
	ll a = rand () % (n - 1) + 1, 
	   c = rand () % (n - 3) + 3;
	ll b = a;
	a = (ksc (a, a, n) + c) % n;
	b = (ksc (b, b, n) + c) % n,
	b = (ksc (b, b, n) + c) % n;
	for (int lim = 1; a != b; lim = min (lim << 1, 128)) 
	{
		ll cnt = 1;
		for (int stp = 1; stp <= lim; stp++) 
		{
			ll tmp = ksc (cnt, abs (b - a), n);
			if (!tmp) break;
			cnt = tmp;
			a = (ksc (a, a, n) + c) % n;
			b = (ksc (b, b, n) + c) % n,
			b = (ksc (b, b, n) + c) % n;
		}
		ll d = gcd (cnt, n);
		if (d != 1) return d;
	}
	return n;
}
ll ans = 0;
void Get_Maxfactor (ll n) 
{
	ll d = Pollard_Rho (n), di;
	while (d == n) d = Pollard_Rho (n);
	di = n / d;
	if (Miller_Robin (d)) ans = max (ans, d);
	else Get_Maxfactor (d);
	if (Miller_Robin (di)) ans = max (ans, di);
	else Get_Maxfactor (di);
	return;
}
int main ()
{
	scanf ("%d", &t);
	while (t--) 
	{
		ll x;
		scanf ("%lld", &x);
		if (Miller_Robin (x)) 
			printf ("Prime\n");
		else 
		{
			ans = 0;
			Get_Maxfactor (x);
			printf ("%lld\n", ans);
		}
			
	}
	return 0;
}

为什么随机化种子就出问题了/kk