Preorder Traversal Java

PROGRAM FOR PREORDER TREE TRAVERSAL

class Node {

    int key;

    Node left, right;

 

    public Node(int item)

    {

        key = item;

        left = right = null;

    }

}

 

class BinaryTree {

    // Root of Binary Tree

    Node root;

 

    BinaryTree() { root = null; }

 

    /* Given a binary tree, print its nodes according to the

      "bottom-up" postorder traversal. */

    void printPostorder(Node node)

    {

        if (node == null)

            return;

 

        // first recur on left subtree

        printPostorder(node.left);

 

        // then recur on right subtree

        printPostorder(node.right);

 

        // now deal with the node

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

    }

 

    /* Given a binary tree, print its nodes in inorder*/

    void printInorder(Node node)

    {

        if (node == null)

            return;

 

        /* first recur on left child */

        printInorder(node.left);

 

        /* then print the data of node */

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

 

        /* now recur on right child */

        printInorder(node.right);

    }

 

    /* Given a binary tree, print its nodes in preorder*/

    void printPreorder(Node node)

    {

        if (node == null)

            return;

 

        /* first print data of node */

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

 

        /* then recur on left sutree */

        printPreorder(node.left);

 

        /* now recur on right subtree */

        printPreorder(node.right);

    }

 

    // Wrappers over above recursive functions

    void printPostorder() { printPostorder(root); }

    void printInorder() { printInorder(root); }

    void printPreorder() { printPreorder(root); }

 

    // Driver method

    public static void main(String[] args)

    {

        BinaryTree tree = new BinaryTree();

        tree.root = new Node(1);

        tree.root.left = new Node(2);

        tree.root.right = new Node(3);

        tree.root.left.left = new Node(4);

        tree.root.left.right = new Node(5);

 

        System.out.println(

            "Preorder traversal of binary tree is ");

        tree.printPreorder();

 

        System.out.println(

            "\nInorder traversal of binary tree is ");

        tree.printInorder();

 

        System.out.println(

            "\nPostorder traversal of binary tree is ");

        tree.printPostorder();

    }

}




OUTPUT:

Preorder traversal of binary tree is
1 2 4 5 3 

CREDITS: https://www.geeksforgeeks.org/tree-traversals-inorder-preorder-and-postorder/