the right way to cloning tree

Question

am trying to understand how clone working with the tree, so I wanted to make a tree that The input and output will be the same tree (that is, the same values in the nodes, the nodes are connected in the same way), but it must consist of different objects so as I understand the clone concept I tried to do that here is my code for better understand;

class Node {
    public int val;
    int key;
    Node left, right;

    public Node(int data){
        key = data;
        left = right = null;
    }
}
class binaryTree {

    Node root;

    binaryTree() {
        root = null;
    }


    void preOrder(Node node) {
        if (node == null)
            return;

        System.out.print(node.key + " ");

        preOrder(node.left);

        preOrder(node.right);
    }

    void preOrder_traversal() {
        preOrder(root);
    }


        public Node cloneTree(Node root) {
            if (root == null) return null;
            Node newNode = new Node(root.val);
            newNode.left = cloneTree(root.left);
            newNode.right = cloneTree(root.right);

            return newNode;

        }
    }

this the main class

public class Main {

    public static void main(String[] args) {
        binaryTree tree = new binaryTree();
        /*        45
                //  \\
                10   90
               // \\
               7   12      */
        tree.root = new Node(45);
        tree.root.left = new Node(10);
        tree.root.right = new Node(90);
        tree.root.left.left = new Node(7);
        tree.root.left.right = new Node(12);
         //  Traversal
        System.out.println("        \t\t  45\n"   +
                "                //  \\\\\n" +
                "                10   90\n" +
                "               // \\\\\n" +
                "               7   12    :");

        System.out.print("  \t \t\t" );
        tree.preOrder_traversal();
        System.out.println();
       
        tree.cloneTree(tree.root);
        System.out.print("  \t \t\t" );
        tree.preOrder_traversal();

    }
}

output

45 // \ 10 90 // \ 7 12 : 45 10 7 12 90 45 10 7 12 90

in the cloneTree() function I tried to make a new object from the Node class; is the right way to make an object form the tree or the is a better way

Does this answer your question? [How to deep copy a Binary Tree?](https://stackoverflow.com/questions/16098362/how-to-deep-copy-a-binary-tree) — Martin Niederl, Jun 16 '21 at 20:30

score 0 · Answer 1 · answered Jun 16 '21 at 22:10

The way you do it is fine (although I didn't get the apparent mix up between key and val). It would be even nicer if you would add a Node constructor overload that takes arguments for left and right:

public Node(int data, Node left, Node right) {
    key = data;
    this.left = left;
    this.right = right;
}

Then the cloneTree method could be:

public Node cloneTree(Node root) {
    return root == null ? null 
         : new Node(root.key, cloneTree(root.left), cloneTree(root.right));
}

the right way to cloning tree

1 Answers1