Lowest Common Ancestor in A Binary Search Tree

For a Binary Search Tree, the lowest common ancestor is the lowest node T that has both p and q as descendants (a node can be a descendant of itself)

There are three cases:

• If p and q are > the root’s value, we want to check right, since either p or q is a parent of p and q, not the root.
• If p and q are < the root’s value, we want to check left, since either p or q is a parent of p and q, not the root.
• If this criteria isn’t met, we know the root is the split point, where the current root is the parent.

def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode':
    if p.val > root.val and q.val > root.val:
        return self.lowestCommonAncestor(root.right, p, q)
    elif p.val < root.val and q.val < root.val:
        return self.lowestCommonAncestor(root.left, p, q)
    else:
        return root