1 files changed, 61 insertions, 0 deletions
diff --git a/test/string/lyndon.cpp b/test/string/lyndon.cpp
new file mode 100644
index 0000000..ecf2dad
--- /dev/null
+++ b/test/string/lyndon.cpp
@@ -0,0 +1,61 @@
+#include "../util.h"
+#include <string/lyndon.cpp>
+
+bool isLyndon(string_view s) {
+	string t = string(s) + string(s);
+	for (ll i = 1; i < sz(s); i++) {
+		if (s >= t.substr(i, sz(s))) return false;
+	}
+	return !s.empty();
+}
+
+vector<string> naive(ll n, char mi, char ma) {
+	vector<string> res;
+	auto dfs = [&](auto&& self, string pref)->void{
+		if (sz(pref) <= n && isLyndon(pref)) res.push_back(pref);
+		if (sz(pref) >= n) return;
+		for (char c = mi; c <= ma; c++) {
+			self(self, pref + c);
+		}
+	};
+	dfs(dfs, "");
+	return res;
+}
+
+vector<string> fast(ll n, char mi, char ma) {
+	vector<string> res;
+	string tmp(1, mi);
+	do {
+		res.push_back(tmp);
+	} while (next(tmp, n, mi, ma));
+	return res;
+}
+
+void stress_test() {
+	ll queries = 0;
+	for (ll i = 0; i < 10'000; i++) {
+		int n = Random::integer<int>(1, 6);
+		auto [l, r] = Random::pair<char>('a', 'f');
+		auto got = fast(n, l, r);
+		auto expected = naive(n, l, r);
+		if (got != expected) cerr << "error" << FAIL;
+		queries += sz(expected);
+	}
+	cerr << "tested random queries: " << queries << endl;
+}
+
+constexpr int N = 9;
+void performance_test() {
+	timer t;
+	t.start();
+	auto res = fast(N, 'a', 'f');
+	t.stop();
+	hash_t hash = sz(res);
+	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();
+}