Write a Program to Find N-ary Tree Level Order Traversal

# 429. N-ary Tree Level Order Traversal

Given an n-ary tree, return the level order traversal of its nodes’ values.

Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null value (See examples).

### Example 1:
```
Input: root = [1,null,3,2,4,null,5,6]
Output: [[1],[3,2,4],[5,6]]
```

### Example 2:
```
Input: root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
Output: [[1],[2,3,4,5],[6,7,8,9,10],[11,12,13],[14]]
 ```

Constraints:
```
The height of the n-ary tree is less than or equal to 1000
The total number of nodes is between [0, 104]
```

/**
 * // Definition for a Node.
 * function Node(val,children) {
 *    this.val = val;
 *    this.children = children;
 * };
 */

/**
 * @param {Node|null} root
 * @return {number[][]}
 */
 var levelOrder = function(root) {
    const out = [];
    const bfs = (node, level) => {
        if (!node) {
            return;
        }

        if(level === out.length) {
            out.push([])
        }

        out[level].push(node.val);
        for(const item of node.children) {
            bfs(item, level + 1);
        }
    }
    bfs(root, 0);
    return out;
};