# Problem Definition

## Description

Given a binary tree, return the level order traversal of its nodes’ values. (ie, from left to right, level by level).

**Example:**

Given binary tree

```plaintext
    3
   / \
  9  20
    /  \
   15   7
```

return its level order traversal as:

```plaintext
[
  [3],
  [9,20],
  [15,7]
]
```

Also think about a version of the question where you are asked to do a level order traversal of the tree when depth of the tree is much greater than number of nodes on a level.

## Notes