diff --git a/flake.nix b/flake.nix
index 2117e0c..1bae6b6 100644
--- a/flake.nix
+++ b/flake.nix
@@ -9,6 +9,20 @@
       pkgs = import nixpkgs { inherit system; };
     in
     {
+      packages = rec {
+        u01 = pkgs.callPackage
+          ({ stdenv, catch2_3, cmake }: stdenv.mkDerivation {
+            name = "ecg-u01";
+
+            src = ./u01;
+
+            nativeBuildInputs = [ catch2_3 cmake ];
+
+            doCheck = true;
+          })
+          { };
+      };
+
       devShells.default = pkgs.mkShell {
         nativeBuildInputs = with pkgs; [ catch2_3 cmake ];
       };
diff --git a/u01/CMakeLists.txt b/u01/CMakeLists.txt
new file mode 100644
index 0000000..698d992
--- /dev/null
+++ b/u01/CMakeLists.txt
@@ -0,0 +1,19 @@
+cmake_minimum_required(VERSION 3.20)
+project(ecg-u01)
+
+add_library(ecg_tree SHARED node.cpp)
+add_executable(main main.cpp)
+target_link_libraries(main ecg_tree)
+
+find_package(Catch2 3)
+if(Catch2_FOUND)
+  add_executable(tests tests.cpp)
+  target_link_libraries(tests PRIVATE Catch2::Catch2WithMain ecg_tree)
+
+  include(CTest)
+  include(Catch)
+  catch_discover_tests(tests)
+endif()
+
+install(TARGETS main)
+install(TARGETS ecg_tree DESTINATION lib)
diff --git a/u01/main.cpp b/u01/main.cpp
new file mode 100644
index 0000000..3fa99de
--- /dev/null
+++ b/u01/main.cpp
@@ -0,0 +1,8 @@
+#include "node.h"
+
+int main(int argc, char **argv) {
+  node *root = new node("root");
+  root->add_child(new node("left child"));
+  root->add_child(new node("right child"));
+  delete root;
+}
diff --git a/u01/node.cpp b/u01/node.cpp
new file mode 100644
index 0000000..a8f52b2
--- /dev/null
+++ b/u01/node.cpp
@@ -0,0 +1,19 @@
+#include <iostream>
+
+#include "node.h"
+
+node::~node() {
+  for (node *child : children) {
+    delete child;
+  }
+}
+
+std::string node::get_name() const { return name; }
+
+void node::set_name(const std::string new_name) { this->name = new_name; }
+
+unsigned int node::get_nr_children() const { return children.size(); }
+
+node *node::get_child(std::size_t i) const { return children[i]; }
+
+void node::add_child(node *child) { children.push_back(child); }
diff --git a/u01/node.h b/u01/node.h
new file mode 100644
index 0000000..58d767f
--- /dev/null
+++ b/u01/node.h
@@ -0,0 +1,18 @@
+#include <memory>
+#include <string>
+#include <vector>
+
+class node {
+public:
+  node(const std::string &name);
+  virtual ~node();
+  std::string get_name() const;
+  void set_name(const std::string new_name);
+  unsigned int get_nr_children() const;
+  node *get_child(std::size_t i) const;
+  void add_child(node *child);
+
+private:
+  std::string name;
+  std::vector<node *> children;
+};
diff --git a/u01/tests.cpp b/u01/tests.cpp
new file mode 100644
index 0000000..5faeba6
--- /dev/null
+++ b/u01/tests.cpp
@@ -0,0 +1,35 @@
+#include <catch2/catch_test_macros.hpp>
+#include <iostream>
+
+#include "node.h"
+
+TEST_CASE("Name") {
+  node *n = new node("test");
+  REQUIRE(n->get_name() == "test");
+  n->set_name("foo");
+  REQUIRE(n->get_name() == "foo");
+  delete n;
+}
+
+TEST_CASE("Number of children") {
+  node *n = new node("test");
+  REQUIRE(n->get_nr_children() == 0);
+  for (std::size_t i = 0; i < 20; i++) {
+    node *child = new node("child");
+    n->add_child(child);
+  }
+  REQUIRE(n->get_nr_children() == 20);
+  delete n;
+}
+
+TEST_CASE("Get children") {
+  node *n = new node("test");
+  REQUIRE(n->get_nr_children() == 0);
+  for (std::size_t i = 0; i < 5; i++) {
+    n->add_child(new node("child " + std::to_string(i)));
+  }
+  for (std::size_t i = 0; i < 5; i++) {
+    REQUIRE(n->get_child(i)->get_name() == "child " + std::to_string(i));
+  }
+  delete n;
+}