add: 220312-CN [cpp]

cpp/2203/220312-CN.cpp

@@ -0,0 +1,38 @@
+#include <vector>
+#include <functional>
+
+// Definition for a Node.
+class Node {
+public:
+	int val;
+	std::vector<Node*> children;
+
+	Node(int _val, std::vector<Node*> _children) : val(_val), children(std::move(_children)) {}
+};
+
+/**
+ * 589. N-ary Tree Preorder Traversal
+ * Given the root of an n-ary tree, return the preorder traversal of its nodes' values.
+ * Nary-Tree input serialization is represented in their level order traversal. Each group of children is separated by the null value (See examples)
+ */
+
+/**
+ * 590. N-ary Tree Postorder Traversal
+ * Given the root of an n-ary tree, return the postorder traversal of its nodes' values.
+ * Nary-Tree input serialization is represented in their level order traversal. Each group of children is separated by the null value (See examples)
+ */
+
+class Solution {
+public:
+	static std::vector<int> postorder(Node* root) {
+		std::vector<int> ret;
+		std::function<void(const Node* const)> traverse = [&](const Node* const ptr) {
+			if (!ptr) return;
+			for (const Node* const i : ptr->children)
+				traverse(i);
+			ret.push_back(ptr->val);
+		};
+		traverse(root);
+		return ret;
+	}
+};

cpp/2203/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2203)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2203 220313.cpp)
+ADD_EXECUTABLE(2203 220312-CN.cpp)