What is the Level Order Sum / Averages pattern?

The Level Order Sum / Averages is a common coding interview pattern in Breadth First Search problems. It provides a structured approach to solving related algorithm challenges efficiently.

When should I use Level Order Sum / Averages?

Use the Level Order Sum / Averages pattern when you encounter problems matching its characteristics. Check the "When to Use" and "Clues" sections in the lesson for specific indicators.

Is Level Order Sum / Averages asked in FAANG interviews?

Yes, Level Order Sum / Averages is an essential pattern commonly tested in FAANG and top tech company technical interviews.

Breadth-First Search

Medium

Level Order Sum / Averages

Calculate the sum or average of nodes at each level.

10 min

Solve on LeetCode

Problem Understanding

Given a binary tree, we often need to aggregate data per level.

Goal: Calculate the Sum (or Average, or Max) of all node values for each individual level.
Example: Root 1 (Sum 1). Children 2, 3 (Sum 5). Grandchildren 4, 5, 6 (Sum 15).

Algorithm Strategy

We use standard BFS with a Queue.

Level Loop: Maintain a size variable level_size = queue.length.
Accumulator: Inside the level processing loop, reset a current_level_sum = 0.
Process: As we dequeue nodes, add node.val to current_level_sum.
Result: After the inner loop finishes (level complete), store or compare the sum.

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