1 files changed, 79 insertions, 0 deletions
diff --git a/test/graph/cycleCounting.cpp b/test/graph/cycleCounting.cpp
new file mode 100644
index 0000000..8e53aec
--- /dev/null
+++ b/test/graph/cycleCounting.cpp
@@ -0,0 +1,79 @@
+#include "../util.h"
+#include <datastructures/unionFind.cpp>
+#include <graph/cycleCounting.cpp>
+
+int naive(const vector<pair<int, int>>& edges, int n) {
+	int res = 0;
+	for (int i = 1; i < (1ll << sz(edges)); i++) {
+		vector<int> deg(n);
+		init(n);
+		int cycles = 0;
+		for (int j = 0; j < sz(edges); j++) {
+			if (((i >> j) & 1) != 0) {
+				auto [a, b] = edges[j];
+				deg[a]++;
+				deg[b]++;
+				if (findSet(a) != findSet(b)) {
+					unionSets(a, b);
+				} else {
+					cycles++;
+				}
+			}
+		}
+		bool ok = cycles == 1;
+		for (auto d : deg) ok &= d == 0 || d == 2;
+		if (ok) res++;
+	}
+	return res;
+}
+
+void stress_test() {
+	ll queries = 0;
+	for (int tries = 0; tries < 50'000; tries++) {
+		int n = Random::integer<int>(1, 8);
+		int m = Random::integer<int>(0, min<int>(15, n*(n-1) / 2 + 1));
+
+		Graph<NoData, 0, 1, 1> g(n);
+		g.erdosRenyi(m);
+		vector<pair<int, int>> edges;
+		cycles cyc(n);
+		g.forEdges([&](int a, int b){
+			edges.emplace_back(a, b);
+			cyc.addEdge(a, b);
+		});
+
+		int expected = naive(edges, n);
+		int got = cyc.count();
+
+		if (got != expected) cerr << "got: " << got << ", expected: " << expected << FAIL;
+		queries += n;
+	}
+	cerr << "tested random queries: " << queries << endl;
+}
+
+constexpr int N = 100;
+constexpr int M = 20;
+void performance_test() {
+	timer t;
+
+	Graph<NoData> g(N);
+	g.tree();
+	g.erdosRenyi(M);
+	cycles cyc(N);
+	g.forEdges([&](int a, int b){
+		cyc.addEdge(a, b);
+	});
+
+	t.start();
+	hash_t hash = cyc.count();
+	cerr << sz(cyc.base) << endl;
+	t.stop();
+
+	if (t.time > 1000) cerr << "too slow: " << t.time << FAIL;
+	cerr << "tested performance: " << t.time << "ms (hash: " << hash << ")" << endl;
+}
+
+int main() {
+	stress_test();
+	performance_test();
+}