Queue – Interview Questions and Practice Problems

A Queue is a linear First-In-First-Out (FIFO) data structure which means that the first element added to the queue will be the first one to be removed. Therefore, once a new element is added to the queue, all elements that were added before have to be removed before the new element can be removed.

 
In this post, we have listed out commonly asked interview questions that use queue data structure:

1. Queue implementation using an array – C, C++, Java, PythonBeginner
2. Queue Implementation using a Linked ListBeginner
3. Implement a stack using the queue data structureMedium
4. Implement a queue using the stack data structureMedium
5. Efficiently print all nodes between two given levels in a binary treeEasy
6. Chess Knight Problem | Find the shortest path from source to destinationHard
7. Shortest path in a maze – Lee AlgorithmMedium
8. Find the shortest safe route in a field with sensors presentHard
9. Flood Fill AlgorithmMedium
10. Count number of islandsMedium
11. Find the shortest path from source to destination in a matrix that satisfies given constraintsHard
12. Generate binary numbers between 1 to n using a queueEasy
13. Calculate the height of a binary treeEasy
14. Delete a binary treeEasy
15. Level order traversal of a binary treeEasy
16. Spiral order traversal of a binary treeMedium
17. Reverse level order traversal of a binary treeEasy
18. Print all nodes of a perfect binary tree in a specific orderHard
19. Print left view of a binary treeEasy
20. Find the next node at the same level as the given node in a binary treeMedium
21. Check if a binary tree is a complete binary tree or notMedium
22. Print diagonal traversal of a binary treeMedium
23. Print corner nodes of every level in a binary treeEasy
24. Invert Binary TreeEasy
25. Find minimum passes required to convert all negative values in a matrixHard
26. Convert a binary tree into a doubly-linked list in spiral orderHard
27. Check if a binary tree is a min-heap or notMedium
28. Invert alternate levels of a perfect binary treeHard
29. Convert a Binary Search Tree into a Min HeapHard
30. Snake and Ladder ProblemHard
31. Find the shortest distance of every cell from a landmine inside a mazeHard
32. Convert a multilevel linked list to a singly linked listMedium
33. Check if an undirected graph contains a cycle or notMedium
34. Find maximum cost path in a graph from a given source to a given destinationMedium
35. Total paths in a digraph from a given source to a destination having exactly m edgesMedium
36. Least cost path in a digraph from a given source to a destination having exactly m edgesMedium
37. Breadth-First Search (BFS)Medium
38. Traverse a given directory using BFS and DFS in JavaEasy
39. Perform vertical traversal of a binary treeMedium
40. Compute the maximum number of nodes at any level in a binary treeEasy
41. Print right view of a binary treeMedium
42. Find the minimum depth of a binary treeEasy
43. Depth-First Search (DFS) vs Breadth-First Search (BFS)Beginner
44. Bipartite GraphMedium
45. Compute the least cost path in a weighted digraph using BFSMedium
46. Find the path between given vertices in a directed graphEasy
47. Construct a directed graph from an undirected graph that satisfies given constraintsMedium
48. Print nodes of a binary tree in vertical orderMedium