Solutions

# Recursive or iterative.
# trees

# Recursive - O(log n) time, O(log n) space
def lowestCommonAncestor(root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode':

    if root.val < p.val and root.val < q.val:
        return lowestCommonAncestor(root.right, p, q)
    elif root.val > p.val and root.val > q.val:
        return lowestCommonAncestor(root.left, p, q)
    else: 
        return root

# Iterative - O(log n) time, O(1) space
def lowestCommonAncestor(root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode':
    while root:
        if root.val < p.val and root.val < q.val:
            root = root.right
        elif root.val > p.val and root.val > q.val:
            root = root.left
        else:
            return root
    return None