1 files changed, 47 insertions, 0 deletions
diff --git a/test/math/chineseRemainder.cpp b/test/math/chineseRemainder.cpp
new file mode 100644
index 0000000..26e71de
--- /dev/null
+++ b/test/math/chineseRemainder.cpp
@@ -0,0 +1,47 @@
+#include "../util.h"
+#include <math/extendedEuclid.cpp>
+#include <math/chineseRemainder.cpp>
+
+struct NAIVE {
+	vector<pair<ll, ll>> added;
+	void add(ll a, ll m) {
+		added.emplace_back(a, m);
+	}
+	ll sol() const {
+		ll n = 1;
+		for (auto [_, x] : added) n = lcm(n, x);
+		for (ll i = 0; i < n; i++) {
+			bool ok = true;
+			for (auto [a, m] : added) {
+				ok &= (i % m) == a;
+			}
+			if (ok) return i;
+		}
+		return -1;
+	}
+};
+
+void stress_test() {
+	ll queries = 0;
+	ll withSol = 0;
+	for (ll i = 0; i < 100'000; i++) {
+		CRT crt;
+		NAIVE naive;
+		for (ll j = 0; j < 3; j++) {
+			int m = Random::integer<int>(1, 50);
+			int a = Random::integer<int>(0, m);
+			crt.add(a, m);
+			naive.add(a, m);
+		}
+		if (crt.hasSol != (naive.sol() >= 0)) cerr << "error" << FAIL;
+		if (crt.hasSol && crt.sol != naive.sol()) cerr << "got: " << (ll)crt.sol << ", expected: " << naive.sol() << FAIL;
+		queries += crt.M;
+		withSol += crt.hasSol;
+	}
+	cerr << "tested queries: " << queries << "(" << withSol << ")" << endl;
+}
+
+int main() {
+	stress_test();
+}
+