Tree to List Conversion

Given a binary tree, convert it into a list of lists where each list represents the values of the nodes at that depth of the tree. Input consists of multiple lines where the first line contains an integer n (the number of nodes), followed by n lines each containing an integer value for the node. If the tree is empty (n = 0), output should be an empty list. The output should be printed as a single line JSON array of arrays. Example: Input: 4 1 2 3 4 Output: [[1], [2, 3], [4]]