Is Average of Levels in Binary Tree easy or hard?

Average of Levels in Binary Tree is categorized as an Easy problem. The logic relies on basic tree traversal, particularly level-order traversal with BFS. Once you understand how to process nodes level by level, implementing the average calculation is straightforward.

Average of Levels in Binary Tree Python/Java solution

In Python or Java, the typical implementation uses a queue for BFS. For each level, iterate through the nodes currently in the queue, accumulate their values, and enqueue their children. After processing the level, divide the total by the number of nodes to compute the average.

How to solve Average of Levels in Binary Tree in O(n)?

Traverse the tree once and compute level-wise sums. Using BFS, process nodes level by level with a queue, sum their values, and divide by the number of nodes in that level. Alternatively, use DFS with recursion while storing cumulative sums and counts per depth. Both strategies achieve O(n) time complexity.

What is the best approach for Average of Levels in Binary Tree?

Breadth-First Search (BFS) using a queue is the most direct solution. Level-order traversal naturally processes nodes level by level, allowing you to compute the sum and count of nodes for each level in one pass. The approach runs in O(n) time and uses O(w) space where w is the maximum width of the tree.

Is Average of Levels in Binary Tree asked at Google/Amazon/Meta?

Binary tree traversal problems like this frequently appear in interviews at companies such as Amazon, Google, Meta, and Microsoft. Variations often test level-order traversal, aggregation per level, or tree-based statistics. Interviewers use them to evaluate understanding of BFS and DFS patterns.

What data structure is used in Average of Levels in Binary Tree?

The primary data structure is a queue when using the BFS approach to perform level-order traversal. For the DFS approach, recursion is used along with arrays or lists that store the cumulative sum and node count for each depth level.

What is the time complexity of Average of Levels in Binary Tree?

The time complexity is O(n) because each node in the binary tree is visited exactly once. Both BFS and DFS solutions perform a single traversal of the tree. The difference lies mainly in space usage depending on the traversal method.

Description Solution Video 6:25

637. Average of Levels in Binary Tree

Easy74.8% acceptance4 companies

Given the root of a binary tree, return the average value of the nodes on each level in the form of an array. Answers within 10^-5 of the actual answer will be accepted.

Example 1:

Input: root = [3,9,20,null,null,15,7]
Output: [3.00000,14.50000,11.00000]
Explanation: The average value of nodes on level 0 is 3, on level 1 is 14.5, and on level 2 is 11.
Hence return [3, 14.5, 11].

Example 2:

Input: root = [3,9,20,15,7]
Output: [3.00000,14.50000,11.00000]

Constraints:

The number of nodes in the tree is in the range [1, 10⁴].
-2³¹ <= Node.val <= 2³¹ - 1

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637. Average of Levels in Binary Tree

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