Zigzag Level Order Traversal

Step0/22

Visited0

Result[]

Python Code

22            for _ in range(level_size):
●                node = queue.popleft()
24                level.append(node.val)
25 
26                if node.left:
27                    queue.append(node.left)
28                if node.right:
......
30 
31            if not left_to_right:
32                level.reverse()
......
34            result.append(level)
35            left_to_right = not left_to_right
36

Current Line (23): Dequeue Node

Tree Structure

Operation:Dequeue

Traversal Progress

Current Node

Phase

Queue Management

Zigzag Level Output

Traversal result appears here...

[]

Visit Sequence

Node visit chips appear here...

Step 1: Dequeue

Queue Snapshot

Stack is empty. Click Next to begin!

Step Explanation

Ready to Start Zigzag Traversal

Click "Next Step" to begin. We process tree levels with BFS, alternating output direction each level.

> Start with queue initialized to root.
> Track level boundaries using queue length.
> Watch highlighted line, queue snapshot, and nested result together.

Unvisited

Enqueued Left

Dequeued

Enqueued Right / Processing

Done