diff --git a/cpp/2305/data_structure.h b/cpp/2305/data_structure.h
new file mode 100644
index 0000000..27ce1ba
--- /dev/null
+++ b/cpp/2305/data_structure.h
@@ -0,0 +1,28 @@
+#ifndef LEETCODE_CPP_DATA_STRUCTURE_H
+#define LEETCODE_CPP_DATA_STRUCTURE_H
+
+struct ListNode {
+	int val;
+	ListNode* next;
+
+	explicit ListNode(int x = 0, ListNode* next = nullptr) : val(x), next(next) {}
+};
+
+ListNode* construct(int x) {
+	return new ListNode(x);
+}
+
+template<typename... Ts>
+ListNode* construct(int x, Ts... xs) {
+	return new ListNode(x, construct(xs...));
+}
+
+struct TreeNode {
+	int val;
+	TreeNode* left;
+	TreeNode* right;
+
+	explicit TreeNode(int x, TreeNode* left = nullptr, TreeNode* right = nullptr) : val(x), left(left), right(right) {}
+};
+
+#endif //LEETCODE_CPP_DATA_STRUCTURE_H