Add iteration and unique check

exercise1/main.cpp

@@ -2,7 +2,8 @@
 
 #include "node.h"
 
-int main() {
+int main()
+{
 	/*
 	Node* root = new Node("root");
 	Node* left_child = new Node("left child");
@@ -14,11 +15,26 @@ int main() {
 	delete root;
 	*/
 
+	/*
 	Node *auto_root = Node::create_complete_tree(2, 4);
 
 	std::cout << auto_root << std::endl;
 
 	delete auto_root;
+	*/
+
+	// cycle test
+	Node *root = new Node;
+	Node *child1 = new Node;
+	Node *child2 = new Node;
+
+	root->add_child(child1);
+	root->add_child(child2);
+
+	// add cycle
+	child1->add_child(root);
+
+	std::cout << root << std::endl;
 
 	return 0;
 }

exercise1/node.cpp

@@ -64,8 +64,7 @@ void Node::add_child(Node* child)
 
 void Node::print(std::ostream &str, uint32_t depth) const
 {
-    auto predicate = [&str](const Node* node, uint32_t depth)
-    {
+    auto predicate = [&str](const Node *node, uint32_t depth) {
         for (uint32_t i = 0; i < depth; i++)
         {
             str << "\t";
@@ -74,7 +73,7 @@ void Node::print(std::ostream& str, uint32_t depth) const
         str << node->get_name() + "\n";
     };
 
-    Node::traverse_tree(this, predicate);
+    Node::traverse_tree(this, predicate, false);
 }
 
 Node *Node::create_complete_tree(uint32_t nr_child_nodes, uint32_t tree_depth)
@@ -101,13 +100,74 @@ Node* Node::create_complete_tree(uint32_t nr_child_nodes, uint32_t tree_depth)
     return node;
 }
 
-void Node::traverse_tree(const Node* node, std::function<void(const Node*, uint32_t)> predicate, uint32_t depth)
+void Node::traverse_tree(const Node *node, std::function<void(const Node *, uint32_t)> predicate, bool recursive, uint32_t depth)
 {
+    if (recursive)
+    {
+        std::set<const Node *> visited;
+        traverse_tree_recursive(node, predicate, visited, depth);
+    }
+    else
+    {
+        traverse_tree_iterative(node, predicate, depth);
+    }
+}
+
+void Node::traverse_tree_recursive(const Node *node, std::function<void(const Node *, uint32_t)> predicate, std::set<const Node *> &visited, uint32_t depth)
+{
+    if (visited.find(node) != visited.end())
+    {
+        return;
+    }
+
     predicate(node, depth);
 
+    visited.insert(node);
+
     for (Node *child : node->children)
     {
-        Node::traverse_tree(child, predicate, depth + 1);
+        Node::traverse_tree_recursive(child, predicate, visited, depth + 1);
+    }
+}
+
+void Node::traverse_tree_iterative(const Node *node, std::function<void(const Node *, uint32_t)> predicate, uint32_t depth)
+{
+    struct NodeInfo
+    {
+        const Node *node;
+        uint32_t depth;
+    };
+
+    std::set<const Node *> visited;
+    std::vector<NodeInfo> stack;
+
+    NodeInfo info = {.node = node, .depth = 0};
+    stack.emplace_back(info);
+
+    while (!stack.empty())
+    {
+        // get the last node and remove it from the stack
+        NodeInfo current = stack.back();
+        stack.pop_back();
+
+        // check if we already visited this node
+        if (visited.find(current.node) != visited.end())
+        {
+            continue;
+        }
+
+        // execute given function
+        predicate(current.node, current.depth);
+
+        // mark this node as visited
+        visited.insert(current.node);
+
+        // push children to the stack
+        for (auto child = current.node->children.rbegin(); child != current.node->children.rend(); child++)
+        {
+            NodeInfo info = {.node = *child, .depth = current.depth + 1};
+            stack.emplace_back(info);
+        }
     }
 }
 

exercise1/node.h

@@ -6,8 +6,10 @@
 #include <sstream>
 #include <functional>
 #include <iostream>
+#include <set>
 
-class Node {
+class Node
+{
 
   public:
     Node(const std::string &name = "");
@@ -22,13 +24,16 @@ public:
 
     void print(std::ostream &str = std::cout, uint32_t depth = 0) const;
     static Node *create_complete_tree(uint32_t nr_child_nodes, uint32_t tree_depth);
-    static void traverse_tree(const Node* node, std::function<void(const Node*, uint32_t)> predicate, uint32_t depth = 0);
+    static void traverse_tree(const Node *node, std::function<void(const Node *, uint32_t)> predicate, bool recursive, uint32_t depth = 0);
 
   private:
     std::string name;
     std::vector<Node *> children;
 
     static uint32_t node_id;
+
+    static void traverse_tree_recursive(const Node *node, std::function<void(const Node *, uint32_t)> predicate, std::set<const Node *> &visited, uint32_t depth = 0);
+    static void traverse_tree_iterative(const Node *node, std::function<void(const Node *, uint32_t)> predicate, uint32_t depth = 0);
 };
 
 extern std::ostream &operator<<(std::ostream &os, const Node *node);