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# Level Order

Problem Description

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

Problem Constraints

1 <= number of nodes <= 105

Input Format

First and only argument is root node of the binary tree, A.

Output Format

Return a 2D integer array denoting the zigzag level order traversal of the given binary tree.

Example Input

Input 1:

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

Input 2:

```   1
/ \
6   2
/
3```

Example Output

Output 1:

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

Output 2:

``` [
[1]
[6, 2]
[3]
]```

Example Explanation

Explanation 1:

` Return the 2D array. Each row denotes the traversal of each level.`

NOTE: You only need to implement the given function. Do not read input, instead use the arguments to the function. Do not print the output, instead return values as specified. Still have a question? Checkout Sample Codes for more details.
Hints
• Hint 1
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## Discussion

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