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 listed out commonly asked interview questions that use binary tree:

1. Inorder Tree TraversalMedium
2. Preorder Tree TraversalMedium
3. Postorder Tree TraversalMedium
4. Check if two binary trees are identical or notEasy
5. Print bottom view of a binary treeMedium
6. Print top view of a binary treeMedium
7. In-place convert a binary tree to its sum treeEasy
8. Determine whether the given binary tree nodes are cousins of each otherMedium
9. Print cousins of a given node in a binary treeMedium
10. Check if a binary tree is a sum tree or notMedium
11. Combinations of words formed by replacing given numbers with corresponding alphabetsHard
12. Determine whether a binary tree is a subtree of another binary treeMedium
13. Find the diameter of a binary treeMedium
14. Check if a binary tree is symmetric or notEasy
15. Convert a binary tree to its mirrorEasy
16. Determine if a binary tree can be converted to another by doing any number of swaps of childrenEasy
17. Find the Lowest Common Ancestor (LCA) of two nodes in a binary treeMedium
18. Print all paths from the root to leaf nodes of a binary treeEasy
19. Find ancestors of a given node in a binary treeMedium
20. Find distance between given pairs of nodes in a binary treeHard
21. Find the diagonal sum of a binary treeMedium
22. Sink nodes containing zero to the bottom of a binary treeHard
23. Convert a binary tree to a full tree by removing half nodesMedium
24. Truncate a binary tree to remove nodes that lie on a path having a sum less than kMedium
25. Find maximum sum root to leaf path in a binary treeMedium
26. Check if a binary tree is height-balanced or notMedium
27. Convert binary tree to Left-child right-sibling binary treeMedium
28. Print all paths from leaf to root node of a binary treeMedium
29. Iteratively print the leaf to root path for every leaf node in a binary treeMedium
30. Build a binary tree from a parent arrayHard
31. Find all nodes at a given distance from leaf nodes in a binary treeHard
32. Count all subtrees having the same value of nodes in a binary treeMedium
33. Find the maximum difference between a node and its descendants in a binary treeMedium
34. Find the maximum sum path between two leaves in a binary treeHard
35. Construct a binary tree from inorder and preorder traversalHard
36. Construct a binary tree from inorder and postorder traversalsHard
37. Construct a binary tree from inorder and level order sequenceHard
38. Construct a full binary tree from the preorder sequence with leaf node informationHard
39. Construct a full binary tree from a preorder and postorder sequenceHard
40. Find postorder traversal of a binary tree from its inorder and preorder sequenceMedium
41. Set next pointer to the inorder successor of all nodes in a binary treeEasy
42. Find preorder traversal of a binary tree from its inorder and postorder sequenceHard
43. Find difference between sum of all nodes present at odd and even levels in a binary treeEasy
44. Clone a binary tree with random pointersHard
45. Threaded Binary Tree – Overview and ImplementationMedium
46. Determine if a binary tree satisfies the height-balanced property of a red–black treeMedium
47. Construct an ancestor matrix from a binary treeEasy
48. Find all possible binary trees having the same inorder traversalHard
49. Perform boundary traversal on a binary treeMedium
50. Check if each node of a binary tree has exactly one childEasy
51. Evaluate a Binary Expression TreeEasy
52. Construction of an expression treeEasy
53. Fix children-sum property in a binary treeMedium
54. Maximum path sum in a binary treeHard
55. Create a mirror of an m–ary treeEasy
56. Print a two-dimensional view of a binary treeEasy
57. Construct a binary tree from an ancestor matrixHard
58. Determine whether a given binary tree is a BST or notMedium
59. Find inorder successor for the given key in a BSTMedium
60. Fix a binary tree that is only one swap away from becoming a BSTHard
61. Find the size of the largest BST in a binary treeHard
62. Print binary tree structure with its contents in C++Medium
63. Maximum Independent Set ProblemMedium
64. Huffman Coding Compression AlgorithmHard
65. Construct a Cartesian tree from an inorder traversalMedium
66. Calculate the height of a binary tree with leaf nodes forming a circular doubly linked listMedium
67. Link nodes present in each level of a binary tree in the form of a linked listHard
68. Convert a ternary tree to a doubly-linked listMedium
69. Extract leaves of a binary tree into a doubly-linked listMedium
70. Find the vertical sum of a binary treeHard
71. In-place convert a binary tree to a doubly-linked listHard
72. Check whether the leaf traversal of given binary trees is the same or notHard
73. Efficiently print all nodes between two given levels in a binary treeEasy
74. Calculate the height of a binary treeEasy
75. Delete a binary treeEasy
76. Level order traversal of a binary treeEasy
77. Spiral order traversal of a binary treeMedium
78. Reverse level order traversal of a binary treeEasy
79. Print all nodes of a perfect binary tree in a specific orderHard
80. Print left view of a binary treeEasy
81. Find the next node at the same level as the given node in a binary treeMedium
82. Check if a binary tree is a complete binary tree or notMedium
83. Print diagonal traversal of a binary treeMedium
84. Print corner nodes of every level in a binary treeEasy
85. Invert Binary TreeEasy
86. Convert a binary tree into a doubly-linked list in spiral orderHard
87. Check if a binary tree is a min-heap or notMedium
88. Invert alternate levels of a perfect binary treeHard
89. Perform vertical traversal of a binary treeMedium
90. Compute the maximum number of nodes at any level in a binary treeEasy
91. Print right view of a binary treeMedium
92. Find the minimum depth of a binary treeEasy
93. Depth-First Search (DFS) vs Breadth-First Search (BFS)Beginner
94. Print nodes of a binary tree in vertical orderMedium

 
Also See:

Binary Search Tree (BST) – Interview Questions and Practice Problems