98 validate binary search tree

def (self, root, min, max):
    if root == None:
      return True
    if not root.left and not root.right:
      return root.val < max and root.val > min
    if root.val < min or root.val >= max:
      return False
    return self.ValidBST(root.left, min, root.val) and self.ValidBST(root.right, root.val, max)

def isValidBST(self, root):
    return self.ValidBST(root, -2147483649, 2147483648)