Max Leaf Depth

Given a binary tree, determine the maximum depth of the leaves. The depth of a leaf is defined as the number of edges from the root to that leaf. If the tree is empty, return 0. For example, given the following tree: 1 / \ 2 3 / 4 / \ 5 6 The maximum leaf depth is 3 (the leaf 5 has a maximum depth of 3). Input Format: A list of integers representing the tree in level order, where -1 indicates a null node. Output Format: An integer representing the maximum leaf depth.