Reverse Level Order Traversal of a Binary Tree using Recursion

class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right

def reverseLevelOrder(root):
    levels = []
    def helper(node, level):
        if not node:
            return
        if len(levels) == level:
            levels.append([])
        levels[level].append(node.val)
        helper(node.left, level + 1)
        helper(node.right, level + 1)
    helper(root, 0)
    result = []
    for level in reversed(levels):
        result.extend(level)
    return result

# Example usage:
if __name__ == '__main__':
    # Construct binary tree:
    #         1
    #       /   \
    #      2     3
    #     / \   / \
    #    4   5 6   7
    root = TreeNode(1, TreeNode(2, TreeNode(4), TreeNode(5)), TreeNode(3, TreeNode(6), TreeNode(7)))
    print(reverseLevelOrder(root))