Right_view.java

// JAVA program to print right view of
// Binary Tree

import java.io.*;
import java.util.LinkedList;
import java.util.Queue;

// A Binary Tree Node
//class Node {
//	int data;
//	Node left, right;
//	public Node(int d)
//	{
//		data = d;
//		left = right = null;
//	}
//}

class Right_view {
	Node root;

	// function to print Right view of
	// binary tree
	void rightView(Node root)
	{
		if (root == null) {
			return;
		}

		Queue<Node> q = new LinkedList<>();
		q.add(root);

		while (!q.isEmpty()) {

			// get number of nodes for each level
			int n = q.size();

			// traverse all the nodes of the current level
			for (int i = 0; i < n; i++) {
				Node curr = q.peek();
				q.remove();

				// print the last node of each level
				if (i == n - 1) {
					System.out.print(curr.data);
					System.out.print(" ");
				}

				// if left child is not null add it into
				// the
				// queue
				if (curr.left != null) {
					q.add(curr.left);
				}

				// if right child is not null add it into
				// the
				// queue
				if (curr.right != null) {
					q.add(curr.right);
				}
			}
		}
	}

	// Driver code
	public static void main(String[] args)
	{

		// Let's construct the tree as
		// shown in example
		Right_view tree = new Right_view();
		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);
		tree.root.right.left = new Node(6);
		tree.root.right.right = new Node(7);
		tree.root.right.left.right = new Node(8);

		tree.rightView(tree.root);
	}
}

// This code is contributed by Biswajit Rajak