Update 589. N-ary Tree Preorder Traversal

Medo3-coder · web-flow · commit 6c0a5e312205 · 2022-06-28T17:15:07.000+02:00
diff --git a/Tree/589. N-ary Tree Preorder Traversal b/Tree/589. N-ary Tree Preorder Traversal
@@ -40,3 +40,63 @@ public:
 };
 
 //https://www.youtube.com/watch?v=3E6myDNC49I
+
+
+
+//-----------------------------------------------------itr    sol
+ 
+
+/*
+// Definition for a Node.
+class Node {
+public:
+    int val;
+    vector<Node*> children;
+
+    Node() {}
+
+    Node(int _val) {
+        val = _val;
+    }
+
+    Node(int _val, vector<Node*> _children) {
+        val = _val;
+        children = _children;
+    }
+};
+*/
+
+class Solution {
+public:
+    vector<int> preorder(Node* root) {
+        
+        vector<int> result ;
+        stack<Node*> stk ;
+        
+        if(root == NULL)
+        {
+            return result ;
+        }
+        
+        stk.push(root);                // start by pushing the root node
+        
+        while(!stk.empty())      // loop till stack becomes empty
+        {
+            Node* curr = stk.top();     
+            stk.pop() ;                    // pop the top node
+            result.push_back(curr->val) ;  // and insert it into result
+            
+            // loop from all children from right to left & push them into stack
+            for(auto it = curr->children.rbegin() ; it != curr->children.rend() ; ++it )
+            {
+                stk.push(*it);
+            }
+        }
+        
+        return result ;
+    }
+};
+
+
+
+// [3,2,4]  to psuh into stack using rbegin()    like 4 2 3 to pop 3 at first this preorder 
