4.2

4.2/iterate_list.cpp

@@ -0,0 +1,35 @@
+#include <iostream>
+#include <memory>
+
+template <typename T>
+struct Node
+{
+    T value;
+    std::unique_ptr<Node<T>> next;
+};
+
+template <typename T>
+std::size_t countStep(const std::unique_ptr<Node<T>>& node, std::size_t i)
+{
+    return (node)
+         ? countStep(node->next, i + 1)
+         : i;
+}
+
+template <typename T>
+std::size_t count(const std::unique_ptr<Node<T>>& head)
+{
+    return countStep(head, 0);
+}
+
+int main()
+{
+    using NodeT = Node<int>;
+
+    auto head = std::make_unique<NodeT>(NodeT{5, nullptr});
+    head->next = std::make_unique<NodeT>(NodeT{12, nullptr});
+    head->next->next = std::make_unique<NodeT>(NodeT{35, nullptr});
+    head->next->next->next = std::make_unique<NodeT>(NodeT{1, nullptr});
+
+    std::cout << "Size: " << count(head) << '\n';
+}