CodeParkGiven the root of a binary tree, return its values row by row, from the top row down. Each row is an array of values, read from left to right.
- Return an array of arrays.
result[0]holds the root,result[1]holds the root's children, and so on. - An empty tree returns
[]. - Values may be negative or repeated.
- The tree has up to 150,000 nodes.
Input: root = [3, 9, 20, null, null, 15, 7]
Output: [[3], [9, 20], [15, 7]]
Input: root = [1, 2, null, 3]
Output: [[1], [2], [3]]
Input: root = []
Output: []