Timer is Running

Write a function to print Boundary Traversal of a binary tree. Boundary Traversal of a binary tree here means that you have to print boundary nodes of the binary tree Anti-Clockwise starting from the root.
Note: Boundary node means nodes present at the boundary of left subtree and nodes present at the right subtree also including leaf nodes.
For the below tree, the function should print 20 8 4 10 14 25 22 .












Input :
The first line of input contains the number of test cases T. For each test case, there will be only a single line of input which is a string representing the tree as described below: 

  1. The values in the string are in the order of level order traversal of the tree where, numbers denote node values, and a character “N” denotes NULL child.

  2. For example:

    For the above tree, the string will be: 1 2 3 N N 4 6 N 5 N N 7 N

The function should print the Boundary traversal of the tree.

Your Task:
This is a function problem. You don't have to take input. Just complete the function printBoundary() that takes the root node as input and returns an array containing the boundary values in anti-clockwise.

Expected Time Complexity: O(N). 
Expected Auxiliary Space: O(Height of the Tree).

1 <=T<= 30

1 <= Number of nodes<= 105
1 <= Data of a node<= 105



1 2 3
10 20 30 40 60

1 2 3
10 20 40 60 30

Testcase 1:

The first test case represents a tree with 3 nodes and 2 edges where the root is 1, the left child of 1 is 2 and the right child of 1 is 3. And boundary traversal of this tree prints nodes as 1 2 3.

** For More Input/Output Examples Use 'Expected Output' option **

Contributor: Amit Khandelwal, Harshit Sidhwa
Author: Shubham Joshi 1

If you have purchased any course from GeeksforGeeks then please ask your doubt on course discussion forum. You will get quick replies from GFG Moderators there.

Need help with your code? Please use ide.geeksforgeeks.org, generate link and share the link here.

to report an issue on this page.