# Print the Binary Tree in Vertical Order Path.

Objective: Given a binary tree, print it in vertical order path.

What is Vertical Order as you can see in the example above, ,, [1,5,6],, are the verical order of the given binary tree.

Approach:

• Its a tricky solution.
• Do the preordertraversal.
• Take a variable called level, when ever you go left, do level++ AND when ever you go right do level–.
• With step above we have separated out the levels vertically.
• Now you need to store the elements of each level, so create a TreeMap and the (key,value) pair will be (level,elements at that level).
• At the end iterate through the TreeMap and print the results.

Complete Code:

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 import java.util.ArrayList; import java.util.Set; import java.util.TreeMap; public class VerticalOrder { public static TreeMap ht = new TreeMap<>(); public ArrayList al; public void vertical(Node root, int level) { if (root == null) { return; } if (ht.containsKey(level)) { ArrayList x = ht.get(level); x.add(root.data); ht.put(level, x); } else { al = new ArrayList<>(); al.add(root.data); ht.put(level, al); } vertical(root.left, level–1); vertical(root.right, level+1); } public void printResult(TreeMap ht) { Set i = ht.keySet(); for (int keys : i) { System.out.println(ht.get(keys)); } } public static void main(String args[]) { Node root = new Node(1); root.left = new Node(2); root.right = new Node(3); root.left.left = new Node(4); root.left.right = new Node(5); root.right.left = new Node(6); root.right.right = new Node(7); VerticalOrder p = new VerticalOrder(); p.vertical(root, 0); p.printResult(ht); } } class Node { int data; Node left; Node right; public Node(int data) { this.data = data; left = null; right = null; } }

Output:

```

[1, 5, 6]


```