DSA Day 81/100

Topic: Tree

1) Iterative Preorder Traversal

Easy

Question

Input:
        1      
      /          
    4    
  /    \   
4       2

class Node{
     int data;
     Node left,right;
     Node(int d){
         data=d;
         left=right=null;
     }
}

class BinaryTree
{
    static ArrayList<Integer> preorder(Node root)
    {

       ArrayList<Integer> al = new ArrayList<Integer>();
       if(root==null){
           return al;
       }

       Stack<Node> st = new Stack<Node>();
       st.push(root);

       while(!st.isEmpty()){
           root = st.pop();
           al.add(root.data);
            if(root.right!=null){
               st.push(root.right);
           }
           if(root.left!=null){
               st.push(root.left);
           }
       }
       return al;
    }
}

Output: 1 4 4 2

Thank you for reading:)