Binary Tree Node Structure in DSA Typescript - Execution Trace

Concept Flow - Binary Tree Node Structure

Create new node

↓

Assign data value

↓

Set left child pointer to null

↓

Set right child pointer to null

↓

Node ready for use in tree

This flow shows how a binary tree node is created with data and two child pointers initialized to null.

Execution Sample

DSA Typescript

class TreeNode {
  data: number;
  left: TreeNode | null;
  right: TreeNode | null;

  constructor(data: number) {
    this.data = data;
    this.left = null;
    this.right = null;
  }
}

This code defines a binary tree node with data and two child pointers initialized to null.

Execution Table

Step	Operation	Node Data	Left Pointer	Right Pointer	Visual State
1	Create node with data=10	10	null	null	┌────────┐ │ data:10│ │ left:∅ │ │ right:∅│ └────────┘
2	Assign data=10	10	null	null	┌────────┐ │ data:10│ │ left:∅ │ │ right:∅│ └────────┘
3	Set left pointer to null	10	null	null	┌────────┐ │ data:10│ │ left:∅ │ │ right:∅│ └────────┘
4	Set right pointer to null	10	null	null	┌────────┐ │ data:10│ │ left:∅ │ │ right:∅│ └────────┘
5	Node ready for use	10	null	null	┌────────┐ │ data:10│ │ left:∅ │ │ right:∅│ └────────┘

💡 Node created with data and both child pointers set to null, ready to be linked in a binary tree.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
data	undefined	10	10	10	10	10
left	undefined	null	null	null	null	null
right	undefined	null	null	null	null	null

Key Moments - 2 Insights

Why are left and right pointers set to null initially?

Because in the execution_table rows 3 and 4, we see left and right pointers assigned null to indicate no children yet. This prevents errors when traversing the tree.

Is the data assigned before or after setting pointers?

Data is assigned first (step 2) before pointers are set (steps 3 and 4), as shown in the execution_table.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of the right pointer after step 3?

A undefined

B 10

C null

D Not set yet

💡 Hint

Check the 'Right Pointer' column in row for step 3 in execution_table.

At which step is the node considered ready for use in the tree?

A Step 3

B Step 5

C Step 4

D Step 2

💡 Hint

Look at the 'Operation' column and 'Visual State' in execution_table for the final step.

If we skip setting left pointer to null, what would be the left pointer value after step 3?

A undefined

B data value

C null

D Error

💡 Hint

Refer to variable_tracker for 'left' variable changes and default initialization.

Concept Snapshot

Binary Tree Node Structure:
- Each node has data, left, and right pointers.
- Data holds the value.
- Left and right pointers start as null (no children).
- Nodes link to form the binary tree.
- Initialize pointers to null to avoid traversal errors.

Full Transcript

This concept shows how to create a binary tree node in TypeScript. The node has three parts: data, left pointer, and right pointer. We first create the node and assign the data value. Then we set the left and right pointers to null, meaning the node has no children yet. This setup is essential before linking nodes to form a binary tree. The execution table traces each step, showing the node's data and pointers. The variable tracker confirms how data and pointers change from undefined to their final values. Key moments clarify why pointers start as null and the order of assignments. The visual quiz tests understanding of pointer values at different steps. The snapshot summarizes the node structure and initialization rules.