add binary lifting test

3 files changed, 118 insertions, 1 deletions

diff --git a/.gitignore b/.gitignore
index 21eab22..2c4d2aa 100644
--- a/.gitignore
+++ b/.gitignore
@@ -220,3 +220,7 @@ TSWLatexianTemp*
 *-tags.tex
 
 *~
+
+# files produced by the testing system
+*.test
+*.ok
diff --git a/Makefile b/Makefile
index 0338a34..b92afb9 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,25 @@
-all:
+TESTS = graph/test/binary_lifting.test
+
+pdf:
 	latexmk -pdf tcr
+
+all: pdf test
+
+test: $(TESTS:.test=.ok)
+
 clean:
 	latexmk -c tcr
 	rm -f *.thm
+	rm -f $(TESTS) $(TESTS:.test=.ok)
+
+%.ok: %.test
+	timeout -v 1 ./$<
+	@touch $@
+%.test: %.cpp
+	g++ -std=gnu++20 -Wall -Wextra -Wpedantic -Werror \
+		-fsanitize=address,undefined -g -o $@ $<
+
+graph/test/binary_lifting.test: graph/test/binary_lifting.cpp \
+	graph/binary_lifting.cpp
+
+.PHONY: all pdf test clean
diff --git a/graph/test/binary_lifting.cpp b/graph/test/binary_lifting.cpp
new file mode 100644
index 0000000..e1cf7d2
--- /dev/null
+++ b/graph/test/binary_lifting.cpp
@@ -0,0 +1,93 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+#include "../binary_lifting.cpp"
+
+mt19937 rd(0);
+
+void test(const vector<vector<int>> &old_adj, int root) {
+	int n = old_adj.size();
+	vector<int> perm(n);
+	iota(perm.begin(), perm.end(), 0);
+	ranges::shuffle(perm, rd);
+	vector<vector<int>> adj(n);
+	for (int i = 0; i < n; i++) {
+		auto &a = adj[perm[i]] = old_adj[i];
+		for (int &v: a) v = perm[v];
+		ranges::shuffle(a, rd);
+	}
+	root = perm[root];
+
+	vector<int> parent(n);
+	function<void(int,int)> dfs = [&](int u, int p) {
+		parent[u] = p;
+		for (int v: adj[u]) if (v != p) dfs(v, u);
+	};
+	dfs(root, -1);
+
+	function<bool(int, int)> is_ancestor = [&](int u, int v) {
+		while (v != -1 && u != v) v = parent[v];
+		return u == v;
+	};
+	function<int(int)> depth = [&](int v) {
+		int r = 0;
+		while ((v = parent[v]) != -1) r++;
+		return r;
+	};
+
+	Lift lift(adj, root);
+	for (int i = 0; i < n; i++) assert(lift.depth(i) == depth(i));
+	uniform_int_distribution<int> distrib(0, n-1);
+	for (int i = 0; i < 1000; i++) {
+		int v = distrib(rd);
+		int d = distrib(rd);
+		int u = lift.lift(v, d);
+		assert(is_ancestor(u, v));
+		if (d <= depth(v)) assert(depth(u) == d);
+		else assert(u == v);
+	}
+	for (int i = 0; i < 1000; i++) {
+		int u = distrib(rd);
+		int v = distrib(rd);
+		int lca = lift.lca(u, v);
+		assert(is_ancestor(lca, u));
+		assert(is_ancestor(lca, v));
+		for (int p = parent[lca]; int c: adj[lca]) {
+			if (c == p) continue;
+			assert(!is_ancestor(c, u) || !is_ancestor(c, v));
+		}
+	}
+}
+
+int main() {
+	{
+		// Single vertex
+		vector<vector<int>> adj(1);
+		test(adj, 0);
+	}
+	{
+		// Path
+		vector<vector<int>> adj(100);
+		for (int i = 1; i < 100; i++) {
+			adj[i-1].push_back(i);
+			adj[i].push_back(i-1);
+		}
+		test(adj, 0);
+		test(adj, 99);
+		test(adj, 40);
+	}
+	{
+		// Random
+		vector<vector<int>> adj(1000);
+		for (int i = 1; i < 1000; i++) {
+			uniform_int_distribution<int> distrib(0, i-1);
+			int p = distrib(rd);
+			adj[p].push_back(i);
+			adj[i].push_back(p);
+		}
+		test(adj, 0);
+		test(adj, 300);
+		test(adj, 600);
+		test(adj, 900);
+	}
+}