1 files changed, 92 insertions, 0 deletions
diff --git a/test/graph/scc.cpp b/test/graph/scc.cpp
new file mode 100644
index 0000000..123050f
--- /dev/null
+++ b/test/graph/scc.cpp
@@ -0,0 +1,92 @@
+#include "../util.h"
+#include <graph/scc.cpp>
+#include <datastructures/unionFind.cpp>
+
+void stress_test() {
+	ll queries = 0;
+	for (int tries = 0; tries < 100'000; tries++) {
+		int n = Random::integer<int>(1, 30);
+		int m = Random::integer<int>(0, max<int>(1, min<int>(100, n*(n-1) / 2 + 1)));
+		Graph<NoData, true> g(n);
+		g.erdosRenyi(m);
+
+		adj.assign(n, {});
+		g.forEdges([](int a, int b){
+			adj[a].push_back(b);
+		});
+		scc();
+
+		vector<bool> tmp(n);
+		for (int i = 0; i < sz(sccs); i++) {
+			for (int x : sccs[i]) {
+				if (tmp[x]) cerr << "error: duclicate" << FAIL;
+				if (idx[x] != i) cerr << "error: inconsistent" << FAIL;
+				tmp[x] = true;
+			}
+		}
+		for (int i = 0; i < n; i++) {
+			if (!tmp[i]) cerr << "error: missing" << FAIL;
+		}
+
+		init(n);
+		vector<ll> seen(n);
+		int tmpCounter = 0;
+		auto reach = [&](int a, int b) {
+			tmpCounter++;
+			seen[a] = tmpCounter;
+			vector<int> todo = {a};
+			while (seen[b] != tmpCounter && !todo.empty()) {
+				a = todo.back();
+				todo.pop_back();
+				g.forOut(a, [&](int /**/, int x){
+					if (seen[x] != tmpCounter) {
+						seen[x] = tmpCounter;
+						todo.push_back(x);
+					}
+				});
+			}
+			return seen[b] == tmpCounter;
+		};
+		for (int a = 0; a < n; a++) {
+			for (int b = 0; b < a; b++) {
+				if (findSet(a) == findSet(b)) continue;
+				if (reach(a, b) && reach(b, a)) unionSets(a, b);
+			}
+		}
+
+		for (int a = 0; a < n; a++) {
+			for (int b = 0; b <= a; b++) {
+				bool got = idx[a] == idx[b];
+				bool expected = findSet(a) == findSet(b);
+				if (got != expected) cerr << "got: " << got << ", expected: " << expected << FAIL;
+			}
+		}
+		queries += n;
+	}
+	cerr << "tested random queries: " << queries << endl;
+}
+
+constexpr int N = 500'000;
+constexpr int M = 2'000'000;
+void performance_test() {
+	timer t;
+	Graph<NoData, true> g(N);
+	g.erdosRenyi(M);
+	adj.assign(N, {});
+	g.forEdges([](int a, int b){
+		adj[a].push_back(b);
+	});
+
+	t.start();
+	scc();	
+	t.stop();
+	hash_t hash = 0;
+	for (int x : idx) hash += x;
+	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();
+}