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Grokking the Coding Interview Patterns in C++

Populating Next Right Pointers in Each Node

Understand how to connect all nodes at the same level in a perfect binary tree by setting each node's next pointer to its immediate right node. Learn to implement a breadth-first search approach that traverses the tree level by level and correctly assigns pointers, enhancing your skills in tree manipulation and coding interview patterns.

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Statement

Given a perfect binary treeA binary tree in which all the levels are completely filled with nodes, and all leaf nodes (nodes with no children) are at the same level., where each node contains an additional pointer called next. This pointer is initially set to NULL for all nodes. Your task is to connect all nodes of the same hierarchical level by setting the next pointer to its immediate right node.

The next pointer of the rightmost node at each level is set to NULL.

Constraints:

  • The number of nodes in the tree is in the range [0,500][0, 500].
  • −1000≤-1000 \leq Node.data ≤1000\leq 1000

Examples

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Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

Populating Next Right Pointers in Each Node

1.

What should be in the next of the node value 15 after making the connections of the tree at every level?

         _______ 25 _______
        |                  |
     __ 14 _            __ 35__
    |       |          |       |
  _ 1_    _ 15 _     - 20 -   200
 |    |  |      |   |      |  |  |
 8    9  10     11  6      7  2  5
A.

20

B.

1

C.

11

D.

200

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Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Sequence - Vertical
Drag and drop the cards to rearrange them in the correct sequence.
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Try it yourself

Implement your solution in PopulatingNextRightPointers.cpp in the following coding playground. You’ll need the provided supporting code to implement your solution.

Note: We have set up the test cases to check the next right nodes of the output tree with connected nodes at each level.

C++
usercode > PopulatingNextRightPointers.cpp
EduTreeNode<int>* PopulateNextPointers(EduTreeNode<int>* root) {
    // Replace this placeholder return statement with your code
    
    return root;
}
Populating Next Right Pointers in Each Node