1 files changed, 38 insertions, 0 deletions
diff --git a/test/math/permIndex.cpp b/test/math/permIndex.cpp
new file mode 100644
index 0000000..6c77d74
--- /dev/null
+++ b/test/math/permIndex.cpp
@@ -0,0 +1,38 @@
+#include "../util.h"
+#include <math/permIndex.cpp>
+
+void stress_test() {
+	ll queries = 0;
+	for (ll i = 0; i < 10'000; i++) {
+		int n = Random::integer<int>(1, 100);
+		vector<ll> cur(n);
+		iota(all(cur), 0);
+		ll expected = 0;
+		do {
+			auto got = permIndex(cur);
+			if (got != expected) cerr << "got: " << got << ", expected: " << expected << FAIL;
+			expected++;
+		} while (expected < 100 && next_permutation(all(cur)));
+		queries += n;
+	}
+	cerr << "tested queries: " << queries << endl;
+}
+
+constexpr int N = 500'000;
+void performance_test() {
+	timer t;
+	vector<ll> cur(N);
+	iota(all(cur), 0);
+	reverse(cur.end() - 10, cur.end());
+	t.start();
+	auto hash = permIndex(cur);
+	t.stop();
+	if (t.time > 500) cerr << "too slow: " << t.time << FAIL;
+	cerr << "tested performance: " << t.time << "ms (hash: " << hash << ")" << endl;
+}
+
+int main() {
+	stress_test();
+	performance_test();
+}
+