Longest Increasing Sequence in BST

Given a Binary Search Tree, find its longest increasing subsequence. The subsequence must maintain the order of the original nodes. The tree node is defined as: class TreeNode: def __init__(self, val=0, left=None, right=None): self.val = val self.left = left self.right = right Return the length of the longest increasing subsequence. Example Input 1 1 2 3