merge mzuenni changes

1 files changed, 44 insertions, 0 deletions

diff --git a/test/math/recover.cpp b/test/math/recover.cpp
new file mode 100644
index 0000000..6f89e5a
--- /dev/null
+++ b/test/math/recover.cpp
@@ -0,0 +1,44 @@
+#include "../util.h"
+#include <math/recover.cpp>
+#include <math/shortModInv.cpp>
+
+void stress_test() {
+	ll queries = 0;
+	timer t;
+	for (int i = 0; i < 500; i++) {
+		ll p = Random::prime<ll>(10000);
+		for (ll j = 0; 2*j*j < p; j++) {
+			for (ll b = 1; 2*b*b < p; b++) {
+				if (gcd(j, b) != 1) continue;
+				for (ll a : {-j, j}) {
+					ll c = a * multInv(b, p);
+					
+					t.start();
+					auto [x, y] = recover(c, p);
+					t.stop();
+
+					if (a != x || b != y) cerr << "got: " << x << "/" << y << ", expected: " << a << "/" << b << FAIL;
+					queries++;
+				}
+			}
+		}
+		for (ll c = 0; c < p; c++) {
+			t.start();
+			auto [x, y] = recover(c, p);
+			t.stop();
+
+			if (y < 0) continue;
+			if (y == 0) cerr << "error: y=0" << FAIL;
+			ll got = (((x * multInv(y, p)) % p) + p) % p;
+			if (got != c) cerr << "got: " << got << ", expected: " << c << FAIL;
+			queries++;
+		}
+	}
+	cerr << "tested random queries: " << queries << endl;
+	if (t.time > 500) cerr << "too slow: " << t.time << FAIL;
+	cerr << "tested performance: " << t.time << "ms" << endl;
+}
+
+int main() {
+	stress_test();
+}