127. Binary Tree Level Order Traversal

PRO

Medium

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Step 0 / 32

Speed: 1.0x

Queue

1

Visited

Empty

Check if tree root is null (it is not).

Variables

currentnull

level0

queue.length1

visited.length0

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Example 1:

Input: root = [3,9,20,null,null,15,7]

Output: [[3],[9,20],[15,7]]

Explanation: The tree has 3 levels: the root (3), the children of the root (9, 20), and the children of 9 and 20 (15, 7).

Example 2:

Input: root = [1]

Output: [[1]]

Explanation: The tree has only one node, the root (1).

Example 3:

Input: root = []

Output: []

Explanation: The tree is empty, so the result is an empty list.

Constraints:

•
•

Time Complexity

O(n)

Space Complexity

O(w)

127. Binary Tree Level Order Traversal

Understand Before Coding

Visualize This Problem

Draw Your Approach

Example 1:

Example 2:

Example 3:

Constraints:

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127. Binary Tree Level Order Traversal

Understand Before Coding

Queue

Visited

Variables

Visualize This Problem

Draw Your Approach

Example 1:

Example 2:

Example 3:

Constraints:

Learn

Topics

Companies

Hint

Use Cases

Queue

Visited

Variables