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Binary Tree Level Order Traversal

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Given the root node of a binary tree, return an array of arrays, where each inner array represents the values of nodes at each level of the tree, traversed from left to right.

The binary tree is represented by a collection of TreeNodes, where each node has optional left and right child nodes, which are also TreeNodes.

A TreeNode has the following interface:

interface TreeNode {
  val: number;
  left: TreeNode | null;
  right: TreeNode | null;
}

Input

Examples

Input: root = [13,null,-55]
Output: [[13],[-55]]
Explanation: The root has two levels: the first level with the value 13, and the second level with the value -55.
Input: root = [1,2,3,4,5,6,7]
Output: [[1],[2,3],[4,5,6,7]]
Explanation: The tree has three levels: [1] at the first level, [2, 3] at the second level, and [4, 5, 6, 7] at the third level.
Input: root = [5,3,8,null,4,7,9]
Output: [[5],[3,8],[4,7,9]]
Explanation: The tree has three levels: [5] at the first level, [3, 8] at the second level, and [4, 7, 9] at the third level.

Constraints

  • 1 <= Number of nodes <= 10,000
  • -100 <= TreeNode.val <= 100

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    Binary Tree Level Order Traversal | Algorithms Interview Questions with Solutions