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Grokking the Coding Interview: Patterns for Coding Questions
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Solution: Binary Tree Level Order Traversal

Problem Statement

Given a binary tree, populate an array to represent its level-by-level traversal. You should populate the values of all nodes of each level from left to right in separate sub-arrays.

Example 1:

Example 2:

Constraints:

  • The number of nodes in the tree is in the range [0, 2000].
  • -1000 <= Node.val <= 1000

Solution

Since we need to traverse all nodes of each level before moving onto the next level, we can use the Breadth First Search (BFS) technique to solve this problem.

We can use a Queue to efficiently traverse in BFS fashion

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