## What is a BST iterator?

Table of Contents

Binary Search Tree Iterator. Implement the BSTIterator class that represents an iterator over the in-order traversal of a binary search tree (BST): BSTIterator(TreeNode root) Initializes an object of the BSTIterator class. The root of the BST is given as part of the constructor.

**What is BST deletion?**

Delete function is used to delete the specified node from a binary search tree. However, we must delete a node from a binary search tree in such a way, that the property of binary search tree doesn’t violate. There are three situations of deleting a node from binary search tree.

**How do you iterate through BST?**

Binary Search Tree Iterator in C++

- There are two methods next and hasNext,
- The next() method will be like −
- curr := stack top element, and pop top element.
- if right of curr is not null, then push inorder successor from the right of node.
- return value of current.
- The hasNext() method will be like −

### What is an iterator object?

In JavaScript an iterator is an object which defines a sequence and potentially a return value upon its termination. Specifically, an iterator is any object which implements the Iterator protocol by having a next() method that returns an object with two properties: value. The next value in the iteration sequence.

**What is iterator in Java?**

An Iterator is an object that can be used to loop through collections, like ArrayList and HashSet. It is called an “iterator” because “iterating” is the technical term for looping. To use an Iterator, you must import it from the java. util package.

**What do you mean by BST?**

binary search tree

In computer science, a binary search tree (BST), also called an ordered or sorted binary tree, is a rooted binary tree data structure whose internal nodes each store a key greater than all the keys in the node’s left subtree and less than those in its right subtree.

#### How do you delete an element in BST?

1) Node to be deleted is the leaf: Simply remove from the tree. 3) Node to be deleted has two children: Find inorder successor of the node. Copy contents of the inorder successor to the node and delete the inorder successor. Note that inorder predecessor can also be used.

**How do you delete a leaf node in a binary tree?**

Let’s see the steps to solve the problem.

- Write a struct Node for a binary tree.
- Write a function to traverse (inorder, preorder, postorder) through the tree and print all data.
- Initialize the tree by creating nodes with the struct.
- Initialize the x value.
- Write a function to delete the leaf nodes with the given value.

**Why do we need iterator?**

The primary purpose of an iterator is to allow a user to process every element of a container while isolating the user from the internal structure of the container. This allows the container to store elements in any manner it wishes while allowing the user to treat it as if it were a simple sequence or list.

## How to delete a node from a BST?

// Function to delete a node from a BST voiddeleteNode(Node*&root,intkey) // pointer to store the parent of the current node Node*parent=nullptr; // start with the root node Node*curr=root; // search key in the BST and set its parent pointer searchKey(curr,key,parent);

**How to perform inorder traversal on the BST?**

# Function to perform inorder traversal on the BST definorder(root): ifroot isNone: return inorder(root.left) print(root.data,end=’ ‘) inorder(root.right) # Helper function to find minimum value node in the subtree rooted at `curr` defgetMinimumKey(curr): whilecurr.left: curr=curr.left returncurr # Recursive function to insert a key into a BST

**How can I recursively search the key in the BST?**

The auxiliary space required by the program is O(n)for recursion (call stack). The above solution initially searches the key in the BST and also find its parent pointer. We can easily modify the code to recursively search the key in the deletion procedure itself and let recursion take care of updating the parent pointer.

### How do you store a BST node in a class?

# A class to store a BST node classNode: def__init__(self,data,left=None,right=None): self.data=data self.left=left self.right=right # Function to perform inorder traversal on the BST definorder(root): ifroot isNone: return inorder(root.left) print(root.data,end=’ ‘) inorder(root.right)