(self, root, k)
return count[k-1]
:type root: TreeNode
        :type k: int
        :rtype: int
:type root: TreeNode
        :type k: int
        :rtype: int
: type root : TreeNode : type k : int : rtype : int
def kth_smallest(self, root, k):
        """
        :type root: TreeNode
        :type k: int
        :rtype: int
        """
        count = []
        self.helper(root, count)
        return count[k-1]
def kth_smallest ( self , root , k ) : count = [ ] self . helper ( root , count ) return count [ k - 1 ]