Populating Next Right Pointers In Each Node is an example of tree problems. In this post we will see how we can solve in Javascript.

Problem Description

Given a binary tree

struct TreeLinkNode {

  TreeLinkNode *left;

  TreeLinkNode *right;

  TreeLinkNode *next;

}

Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to NULL. Initially, all next pointers are set to NULL.

Note: You may only use constant extra space. You may assume that it is a perfect binary tree (ie, all leaves are at the same level, and every parent has two children).

For example, Given the following perfect binary tree,

     1

   /  \

  2    3

 / \  / \

4  5  6  7

After calling your function, the tree should look like:

     1 -> NULL

   /  \

  2 -> 3 -> NULL

 / \  / \

4->5->6->7 -> NULL

Since it's a full binary tree, our job is much simpler, at each node, connects its left and right child, and try to connect the right child with the left child of node's next. A simple preorder traversal should be able to help us solve this problem.

Solution: Please check the main.js snippet for the solution. If you have different approach in mind or have any suggestion for this implementation feel free to share in the comment below. Thanks!