Left View of Binary Tree Java

PROGRAM TO PRINT LEFT VIEW OF A BINARY TREE

class Node {

    int data;

    Node left, right;

 

    public Node(int item)

    {

        data = item;

        left = right = null;

    }

}

 

/* Class to print the left view */

class BinaryTree {

    Node root;

    static int max_level = 0;

 

    // recursive function to print left view

    void leftViewUtil(Node node, int level)

    {

        // Base Case

        if (node == null)

            return;

 

        // If this is the first node of its level

        if (max_level < level) {

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

            max_level = level;

        }

 

        // Recur for left and right subtrees

        leftViewUtil(node.left, level + 1);

        leftViewUtil(node.right, level + 1);

    }

 

    // A wrapper over leftViewUtil()

    void leftView()

    {

        leftViewUtil(root, 1);

    }

 

    /* testing for example nodes */

    public static void main(String args[])

    {

        /* creating a binary tree and entering the nodes */

        BinaryTree tree = new BinaryTree();

        tree.root = new Node(12);

        tree.root.left = new Node(10);

        tree.root.right = new Node(30);

        tree.root.right.left = new Node(25);

        tree.root.right.right = new Node(40);

 

        tree.leftView();

    }

}




OUTPUT:

12      10      25

CREDITS: https://www.geeksforgeeks.org/print-left-view-binary-tree/