Binary Tree Iterative Inorder Traversal Ask Question Asked 2 days ago Active 2 days ago Viewed 35 times 0 I'm trying to implement an iterative inorder traversal of a binary tree. Process node(15). When there is nothing on left subtree, we move up to the parent and then go to the right subtree. InOrder traversal of Binary tree in Java - Iterative As we did with the iterative pre-order algorithm , you can use a Stack to convert the recursive in order algorithm to an iterative one. Traversal = [1,5,6,10,12], Current node = current.right, i.e null, so pop out of stack. If you want to contribute an share your knowledge with thousands of learners across the … In Binary search tree traversals we discussed different types of traversals like inorder, preorder and postorder traversals. Before the solution, what is an inorder traversal of a binary tree? I hadn’t been satisfied with the way in which the iterative solution of inorder binary tree traversal has been explained so far in my searches on the intertubes. node(6). Again current = current.right which is node(15). In preorder traversal, root node is current = node(1). Get right child of node(10), which is node(14), current = node(14), as current is not null, put it on to stack. We implemented those traversals in a recursive way. In this post, let’s focus on the iterative implementation of inorder traversal or iterative inorder traversal without recursion. As we go into discussion, one quick question: why recursive inorder implementation is not good? For example, for given tree, inorder traversal would be: [1,5,6,10,12,14,15]. Process node(14). In inorder traversal, visit left subtree, then root and at last right subtree. The complexity of iterative implementation of inorder traversal is O(n) with worst-case space complexity of O(n). Please share if there is something wrong or missing. Unlike linked lists, one-dimensional arrays and other linear data structures, which are traversed in linear order, trees may be traversed in multiple ways in depth-first order ( pre-order , in-order , and post-order ) or breadth-first order ( level order traversal ). Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. In inorder traversal, the last node visited before the current node is the parent node. As we refer the most recent node added to structure first (when finding parent of the node, we have to just look at the last visited node), Stack is a great candidate for it which has last in first (LIFO) out property. Traversal = [1,5,6,10,12,14]. We check if the node is null, then return. As recursion goes deep, there will be more return addresses and parameters stored on the stack, eventually filling up all the space a system has for a stack. Fetch right child of the current node which is again null and this time even stack is already empty. current = node(12) which is not null, put it onto the stack. Traversal = [1,5,6], Move to right child of node(6), which is null, so pop from stack current = node(10). Current node is not null, put it on the stack. As there is left child of node(10), move current = current.left, so current = node(5), which is not null, put node on to stack. Necessary cookies are absolutely essential for the website to function properly. This problem is known as stack overflow. Of course, the solution without recursion is not that easy to read but not very difficult to understand. Given a binary tree, write iterative and recursive solution to traverse the tree using post-order traversal in C++, Java and Python. Today we will learn how to do iterative preorder traversal of binary tree. Again move down to the left child, which in this case it is null. What are we essentially doing in recursive implementation? One of the most common things we do on a binary tree is traversal. One thing needs to be thought of is: how to go to parent node? Move to the right child of node(5) i.e. Unlike linked lists, arrays & other linear data structures, which are traversed in linear order, trees may be traversed in multiple ways in depth-first order (in-order… This category only includes cookies that ensures basic functionalities and security features of the website. We know that recursion uses implicitly stack to store return address and passed parameters. When a binary tree is skewed, that is when every node has only one child, a recursive implementation may lead to stack overflow, depending on the size of the tree. Please share if there is something wrong or missing. Let’s take an example and see how this algorithm works. InOrder, traversal can be implemented either recursive and iterative approach. But opting out of some of these cookies may have an effect on your browsing experience.