add binary lifting test

2 files changed, 63 insertions, 3 deletions

diff --git a/content/graph/binary_lifting.cpp b/content/graph/binary_lifting.cpp
index 0b8c218..f88b1a9 100644
--- a/content/graph/binary_lifting.cpp
+++ b/content/graph/binary_lifting.cpp
@@ -3,13 +3,13 @@ struct Lift {
 
 	Lift(vector<vector<int>> &adj, int root):
 			dep(adj.size()), par(adj.size()), jmp(adj.size(), root) {
-		function<void(int,int,int)> dfs = [&](int u, int p, int d) {
+		auto dfs = [&](auto &self, int u, int p, int d) -> void {
 			dep[u] = d, par[u] = p;
 			jmp[u] = dep[p] + dep[jmp[jmp[p]]] == 2*dep[jmp[p]]
 			       ? jmp[jmp[p]] : p;
-			for (int v: adj[u]) if (v != p) dfs(v, u, d+1);
+			for (int v: adj[u]) if (v != p) self(self, v, u, d+1);
 		};
-		dfs(root, root, 0);
+		dfs(dfs, root, root, 0);
 	}
 
 	int depth(int v) { return dep[v]; }
diff --git a/test/graph/binary_lifting.cpp b/test/graph/binary_lifting.cpp
new file mode 100644
index 0000000..20318da
--- /dev/null
+++ b/test/graph/binary_lifting.cpp
@@ -0,0 +1,60 @@
+#include "../util.h"
+#include <graph/binary_lifting.cpp>
+namespace expected {
+#include <graph/hld.cpp>
+}
+
+void stress_test() {
+	ll queries = 0;
+	for (int tries = 0; tries < 200'000; tries++) {
+		int n = Random::integer<int>(2, 30);
+		Graph<NoData> g(n);
+		g.tree();
+
+		vector<vector<int>> adj(n);
+		g.forEdges([&](int a, int b){
+			adj[a].push_back(b);
+			adj[b].push_back(a);
+		});
+
+		Lift lift(adj, 0);
+
+		expected::adj = adj;
+		expected::init();
+
+		for (int i = 0; i < n; i++) {
+			for (int j = 0; j <= i; j++) {
+				auto got = lift.lca(i, j);
+				auto expected = expected::get_lca(i, j);
+				if (got != expected) cerr << "got: " << got  << ", expected: " << expected << FAIL;
+			}
+		}
+		queries += n;
+	}
+	cerr << "tested random queries: " << queries << endl;
+}
+
+constexpr int N = 1'000'000;
+void performance_test() {
+	timer t;
+	Graph<NoData> g(N);
+	g.tree();
+	vector<vector<int>> adj(N);
+	g.forEdges([&](int a, int b){
+		adj[a].push_back(b);
+		adj[b].push_back(a);
+	});
+
+	hash_t hash = 0;
+	t.start();
+	Lift lift(adj, 0);
+	for (int i = 1; i < N; i++) hash += lift.lca(i-1, i);
+	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();
+}