1 files changed, 82 insertions, 0 deletions
diff --git a/test/math/primitiveRoot.cpp b/test/math/primitiveRoot.cpp
new file mode 100644
index 0000000..cd0b388
--- /dev/null
+++ b/test/math/primitiveRoot.cpp
@@ -0,0 +1,82 @@
+#include "../util.h"
+#define ll lll
+#include <math/modPowIterativ.cpp>
+#undef ll
+#include <math/millerRabin.cpp>
+#include <math/rho.cpp>
+
+ll phi(ll pk, ll p, ll /*k*/) {return pk - pk / p;}
+ll phi(ll n) { // O(sqrt(n))
+	ll res = 1;
+	for (ll p = 2; p * p <= n; p++) {
+		if (n % p == 0) {
+			ll pk = 1;
+			ll k = 0;
+			do {
+				n /= p;
+				pk *= p;
+				k++;
+			} while (n % p == 0);
+			res *= phi(pk, p, k);
+	}}
+	if (n > 1) res *= phi(n, n, 1);
+	return res;
+}
+
+#include <math/primitiveRoot.cpp>
+
+bool naiveIsPrimitive(ll g, ll n) {
+	if (gcd(g, n) != 1) return false;
+	vector<bool> seen(n);
+	ll c = g;
+	for (ll i = 0; i < n; i++) {
+		seen[c] = true;
+		c = (c * g) % n;
+	}
+	ll res = 0;
+	for (bool x : seen) if (x) res++;
+	return res == phi(n);
+}
+
+void stress_test() {
+	int queries = 0;
+	for (int tries = 0; tries < 20'000; tries++) {
+		ll a = Random::integer<ll>(1, 3);
+		ll p = Random::prime<ll>(0, 1000);
+		ll k = p == 2 ? 1 : Random::integer<ll>(1, log(100'000) / log(p) + 1);
+
+		ll x = a;
+		for (int i = 0; i < k; i++) x *= p;
+
+		ll got = findPrimitive(x);
+
+		if (got < 0 || got >= x) cerr << "error: out of range" << FAIL;
+		if (!naiveIsPrimitive(got, x)) cerr << "error: wrong" << got << " " << x << FAIL;
+		queries++;
+	}
+	cerr << "tested random queries: " << queries << endl;
+}
+
+void stress_test2() {
+	int queries = 0;
+	for (int x = 2; x < 5'000; x++) {
+		map<ll, int> facts;
+		factor(x, facts);
+		if (x % 2 == 0) facts.erase(facts.find(2));
+		bool expected = sz(facts) == 1;
+		if (x % 4 == 0) expected = false;
+		if (x == 2 || x == 4) expected = true;
+
+		bool got = findPrimitive(x) >= 0;
+
+		if (got != expected) cerr << "error" << FAIL;
+		queries++;
+	}
+	cerr << "tested random queries: " << queries << endl;
+}
+
+int main() {
+	stress_test();
+	stress_test2();
+}
+