# Print the Vertical Sum in binary Tree .

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

What is Vertical Order Sum

as you can see in the example above, [4],[2], [12],[3],[7] are the vertical order sum of the given binary tree.

Approach:

• Do the inorder traversal.
• Take a variable called level, when ever you fo 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 add the elements of each level, so create a TreeMap and the (key,value) pair will be (level,Sum of elements).
• At the end iterate through the TreeMap and print the results.

Complete Code:

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 import java.util.Set; import java.util.TreeMap; public class VerticalOrderSum { public static TreeMap ht = new TreeMap<>();; public static int level; public void vertical(Node root, int level) { if (root == null) { return; } vertical(root.left, level+1); if (ht.get(level) != null) { int y = ht.get(level); ht.put(level, root.data + y); } else { ht.put(level, root.data); } vertical(root.right, level–1); } public void printResult(TreeMap ht) { // Iterator it = ht.keySet().iterator(); Set i = ht.keySet(); for (int keys : i) { System.out.println("Level " + keys + " Sum : " + 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); VerticalOrderSum p = new VerticalOrderSum(); 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:

```Level -2 Sum : 7
Level -1 Sum : 3
Level 0 Sum : 12
Level 1 Sum : 2
Level 2 Sum : 4
```