class Node:
    def __init__(self, val):
        self.val = val
        self.left = None
        self.right = None

def bst_insert(root, newNode):
    if root.val is None:
        raise Exception("Missing root node")
    elif newNode.val is None:
        raise Exception("New node not initialised yet")            
    else:
        if newNode.val > root.val:
            if root.right is None:
                root.right = newNode
            else:
                bst_insert(root.right, newNode)
        elif newNode.val < root.val:
            if root.left is None:
                root.left = newNode
            else:
                bst_insert(root.left, newNode)
        else:
            root.val = val

'''
SAMPLE BST:
          4
     2          5
  1    3    

'''

	
def preorder(root): # root, left, right
    print(root.val)		
    if root.left != None:
        preorder(root.left)
    if root.right != None:
        preorder(root.right)
	
	
def inorder(root): # left, root, right
    if root.left != None:
        inorder(root.left)
    print(root.val)
    if root.right != None:
        inorder(root.right)

def postorder(root): # left, right, root
    if root.left != None:
        postorder(root.left)
    if root.right != None:
        postorder(root.right)
    print(root.val)
    

root = Node(4) 
bst_insert(root, Node(5))
bst_insert(root, Node(2)) 
bst_insert(root, Node(1)) 
bst_insert(root, Node(3))

##print("Preorder traversal of binary tree is")
##preorder(root) 
##  
##print("\nInorder traversal of binary tree is")
##inorder(root) 
##  
##print("\nPostorder traversal of binary tree is")
##postorder(root)

#####################################

'''
          4
     2          5
  1     3


'''

class Iterator:
    def __init__(self, rootNode):
        if rootNode:
            self.rootNode = rootNode
            self.toShow = []
            self.insertIntoStack(rootNode)
                
        else:
            raise Exception("Missing node")
        
    def hasNext(self):
        if len(self.toShow) == 0:
            return False
        else:
            return True

    def next(self):
        node = self.toShow.pop(0)
        self.insertIntoStack(node.right)
        return node.val
        

    def insertIntoStack(self, node):
        if node:
            self.toShow.insert(0, node)
            self.insertIntoStack(node.left)


iterator = Iterator(root)
while(iterator.hasNext()):
    print(iterator.next())
    
        
	

		

3413a992d82e730568cab61bbf6a82558589142e
<mask token>


class Iterator:
    <mask token>

    def hasNext(self):
        if len(self.toShow) == 0:
            return False
        else:
            return True
    <mask token>
    <mask token>


<mask token>

class Node:

    def __init__(self, val):
        self.val = val
        self.left = None
        self.right = None


def bst_insert(root, newNode):
    if root.val is None:
        raise Exception('Missing root node')
    elif newNode.val is None:
        raise Exception('New node not initialised yet')
    elif newNode.val > root.val:
        if root.right is None:
            root.right = newNode
        else:
            bst_insert(root.right, newNode)
    elif newNode.val < root.val:
        if root.left is None:
            root.left = newNode
        else:
            bst_insert(root.left, newNode)
    else:
        root.val = val


<mask token>


def postorder(root):
    if root.left != None:
        postorder(root.left)
    if root.right != None:
        postorder(root.right)
    print(root.val)


<mask token>


class Iterator:

    def __init__(self, rootNode):
        if rootNode:
            self.rootNode = rootNode
            self.toShow = []
            self.insertIntoStack(rootNode)
        else:
            raise Exception('Missing node')

    def hasNext(self):
        if len(self.toShow) == 0:
            return False
        else:
            return True

    def next(self):
        node = self.toShow.pop(0)
        self.insertIntoStack(node.right)
        return node.val

    def insertIntoStack(self, node):
        if node:
            self.toShow.insert(0, node)
            self.insertIntoStack(node.left)


<mask token>

class Node:

    def __init__(self, val):
        self.val = val
        self.left = None
        self.right = None


def bst_insert(root, newNode):
    if root.val is None:
        raise Exception('Missing root node')
    elif newNode.val is None:
        raise Exception('New node not initialised yet')
    elif newNode.val > root.val:
        if root.right is None:
            root.right = newNode
        else:
            bst_insert(root.right, newNode)
    elif newNode.val < root.val:
        if root.left is None:
            root.left = newNode
        else:
            bst_insert(root.left, newNode)
    else:
        root.val = val


<mask token>


def preorder(root):
    print(root.val)
    if root.left != None:
        preorder(root.left)
    if root.right != None:
        preorder(root.right)


<mask token>


def postorder(root):
    if root.left != None:
        postorder(root.left)
    if root.right != None:
        postorder(root.right)
    print(root.val)


<mask token>


class Iterator:

    def __init__(self, rootNode):
        if rootNode:
            self.rootNode = rootNode
            self.toShow = []
            self.insertIntoStack(rootNode)
        else:
            raise Exception('Missing node')

    def hasNext(self):
        if len(self.toShow) == 0:
            return False
        else:
            return True

    def next(self):
        node = self.toShow.pop(0)
        self.insertIntoStack(node.right)
        return node.val

    def insertIntoStack(self, node):
        if node:
            self.toShow.insert(0, node)
            self.insertIntoStack(node.left)


<mask token>

class Node:

    def __init__(self, val):
        self.val = val
        self.left = None
        self.right = None


def bst_insert(root, newNode):
    if root.val is None:
        raise Exception('Missing root node')
    elif newNode.val is None:
        raise Exception('New node not initialised yet')
    elif newNode.val > root.val:
        if root.right is None:
            root.right = newNode
        else:
            bst_insert(root.right, newNode)
    elif newNode.val < root.val:
        if root.left is None:
            root.left = newNode
        else:
            bst_insert(root.left, newNode)
    else:
        root.val = val


<mask token>


def preorder(root):
    print(root.val)
    if root.left != None:
        preorder(root.left)
    if root.right != None:
        preorder(root.right)


def inorder(root):
    if root.left != None:
        inorder(root.left)
    print(root.val)
    if root.right != None:
        inorder(root.right)


def postorder(root):
    if root.left != None:
        postorder(root.left)
    if root.right != None:
        postorder(root.right)
    print(root.val)


root = Node(4)
bst_insert(root, Node(5))
bst_insert(root, Node(2))
bst_insert(root, Node(1))
bst_insert(root, Node(3))
<mask token>


class Iterator:

    def __init__(self, rootNode):
        if rootNode:
            self.rootNode = rootNode
            self.toShow = []
            self.insertIntoStack(rootNode)
        else:
            raise Exception('Missing node')

    def hasNext(self):
        if len(self.toShow) == 0:
            return False
        else:
            return True

    def next(self):
        node = self.toShow.pop(0)
        self.insertIntoStack(node.right)
        return node.val

    def insertIntoStack(self, node):
        if node:
            self.toShow.insert(0, node)
            self.insertIntoStack(node.left)


iterator = Iterator(root)
while iterator.hasNext():
    print(iterator.next())

class Node:
    def __init__(self, val):
        self.val = val
        self.left = None
        self.right = None

def bst_insert(root, newNode):
    if root.val is None:
        raise Exception("Missing root node")
    elif newNode.val is None:
        raise Exception("New node not initialised yet")            
    else:
        if newNode.val > root.val:
            if root.right is None:
                root.right = newNode
            else:
                bst_insert(root.right, newNode)
        elif newNode.val < root.val:
            if root.left is None:
                root.left = newNode
            else:
                bst_insert(root.left, newNode)
        else:
            root.val = val

'''
SAMPLE BST:
          4
     2          5
  1    3    

'''

	
def preorder(root): # root, left, right
    print(root.val)		
    if root.left != None:
        preorder(root.left)
    if root.right != None:
        preorder(root.right)
	
	
def inorder(root): # left, root, right
    if root.left != None:
        inorder(root.left)
    print(root.val)
    if root.right != None:
        inorder(root.right)

def postorder(root): # left, right, root
    if root.left != None:
        postorder(root.left)
    if root.right != None:
        postorder(root.right)
    print(root.val)
    

root = Node(4) 
bst_insert(root, Node(5))
bst_insert(root, Node(2)) 
bst_insert(root, Node(1)) 
bst_insert(root, Node(3))

##print("Preorder traversal of binary tree is")
##preorder(root) 
##  
##print("\nInorder traversal of binary tree is")
##inorder(root) 
##  
##print("\nPostorder traversal of binary tree is")
##postorder(root)

#####################################

'''
          4
     2          5
  1     3


'''

class Iterator:
    def __init__(self, rootNode):
        if rootNode:
            self.rootNode = rootNode
            self.toShow = []
            self.insertIntoStack(rootNode)
                
        else:
            raise Exception("Missing node")
        
    def hasNext(self):
        if len(self.toShow) == 0:
            return False
        else:
            return True

    def next(self):
        node = self.toShow.pop(0)
        self.insertIntoStack(node.right)
        return node.val
        

    def insertIntoStack(self, node):
        if node:
            self.toShow.insert(0, node)
            self.insertIntoStack(node.left)


iterator = Iterator(root)
while(iterator.hasNext()):
    print(iterator.next())
    
        
	

		
