Untitled

import java.util.Map;
import java.util.TreeMap;

class TreeNode {
    int data;
    TreeNode left, right;
    public TreeNode(int data) {
        this.data = data;
    }
}
public class Main {
    /*
         1
       2   3
     5       7
       6       9
     */
     static void rightViewUtil(TreeNode root, int level, Map<Integer, Integer> m) {
        if(root==null) {
            return;
        }
        m.put(level, root.data);
        rightViewUtil(root.left, level+1, m);
        rightViewUtil(root.right, level+1, m);
    }
    static void rightView(TreeNode root) {
        Map<Integer, Integer> m = new TreeMap<>();
        rightViewUtil(root, 0, m);
        for (Map.Entry<Integer, Integer> entry : m.entrySet()){
            System.out.println(entry.getValue());
        }
    }
    public static void main(String[] args) {
        TreeNode root = new TreeNode(1);
        root.left = new TreeNode(2);
        root.right = new TreeNode(3);
        root.left.left = new TreeNode(5);
        root.left.left.right = new TreeNode(6);
        rightView(root);
    }
}