# Binary Tree – Interview Questions and Practice Problems

A Binary Tree is a tree data structure in which each node has at most two children, which are referred to as the left child and the right child and the topmost node in the tree is called the root.

In this post, we have list out commonly asked interview questions that uses binary tree –

• Check if two given binary trees are identical or not
• Calculate height of a binary tree
• Delete given Binary Tree
• Inorder Tree Traversal (Iterative & Recursive Implementation)
• Preorder Tree Traversal (Iterative & Recursive Implementation)
• Postorder Tree Traversal (Iterative & Recursive Implementation)
• Level Order Traversal of Binary Tree
• Spiral Order Traversal of Binary Tree
• Reverse Level Order Traversal of Binary Tree
• Print all nodes of a given binary tree in specific order
• Print left view of binary tree
• Print Bottom View of Binary Tree
• Print Top View of Binary Tree
• Find next node in same level for given node in a binary tree
• Check if given binary tree is complete binary tree or not
• In-place convert given binary tree to its sum tree
• Determine if given two nodes are cousins of each other
• Print cousins of given node in a binary tree
• Check if given binary tree is a sum tree or not
• Combinations of words formed by replacing given numbers with corresponding alphabets
• Determine if given binary tree is a subtree of another binary tree or not
• Find diameter of a binary tree
• Check if given binary Tree has symmetric structure or not
• Convert binary tree to its mirror
• Check if binary tree can be converted to another by doing any no. of swaps of left & right child
• Find Lowest Common Ancestor (LCA) of two nodes in a binary tree
• Print all paths from root to leaf nodes in a binary tree
• Find ancestors of given node in a Binary Tree
• Find the distance between given pairs of nodes in a binary tree
• Find Vertical Sum in a given Binary Tree
• Perform vertical traversal of a binary tree ? I
• Perform vertical traversal of a binary tree ? II
• Print corner nodes of every level in binary tree
• Find the diagonal sum of given binary tree
• Print Diagonal Traversal of Binary Tree
• In-place convert Binary Tree to Doubly Linked List
• Sink nodes containing zero to the bottom of the binary tree
• Convert given binary tree to full tree by removing half nodes
• Truncate given binary tree to remove nodes which lie on a path having sum less than K
• Find maximum sum root-to-leaf path in a binary tree
• Check if given binary tree is height balanced or not
• Find maximum width of given binary tree
• Convert normal binary tree to Left-child right-sibling binary tree
• Determine if given Binary Tree is a BST or not
• Convert a Binary Tree to BST by maintaining its original structure
• Invert a Binary Tree
• Print Right View of a Binary Tree
• Print all paths from leaf to root node in given binary tree
• Iteratively print leaf to root path for every leaf node in a binary tree
• Build Binary Tree from given Parent array
• Find all nodes at given distance from leaf nodes in a binary tree
• Count all subtrees having same value of nodes in a binary tree
• Find Maximum Difference Between a Node and its Descendants in a Binary Tree
• Construct a Binary Tree from Ancestor Matrix
• Calculate height of a binary tree with leaf nodes forming a circular doubly linked list
• Find maximum sum path between two leaves in a binary tree
• Fix a binary tree that is only one swap away from becoming a BST
• Construct a binary tree from inorder and preorder traversal
• Construct a binary tree from inorder and postorder traversals
• Construct a binary tree from inorder and level order sequence
• Construct a full binary tree from preorder sequence with leaf node information
• Construct a full binary tree from a preorder and postorder sequence
• Set next pointer to inorder successor of all nodes in binary tree
• Efficiently print all nodes between two given levels in a binary tree
• Find preorder traversal of a binary tree from its inorder and postorder sequence
• Find the difference between sum of all nodes present at odd and even levels in a binary tree
• Find the size of the largest BST in a Binary Tree
• Link nodes present in each level of a binary tree in the form of a linked list
• Construct a Cartesian Tree from In-order Traversal
• Implementation of Treap Data Structure (Insert, Search and Delete)
• Clone a binary tree with random pointers
• Threaded Binary Tree: Overview and Implementation
• Invert alternate levels of a perfect binary tree
• Convert a Binary Tree into a Doubly Linked List in Spiral Order
• Check if a binary tree is a min-heap or not
• Determine if a binary tree satisfy the height-balanced property of red?black tree
• Depth first search (DFS) vs Breadth first search (BFS)