Stack Data Structure: Practice Problems and Interview Questions

Stack (data structure)

A stack is a linear Last-In-Last-Out (LIFO) data structure which means that the last element added to the stack will be the first one to be removed. Therefore, once a new element is added to the stack, all elements that were added after it has to be removed before the new element can be removed.

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

1. Stack implementation using an array — C, C++, Java, Python
2. Stack Implementation using a Linked List
3. Implement a stack using the queue data structure
4. Implement a queue using the stack data structure
5. Design a stack that returns the minimum element in constant time
6. Design a stack that returns a minimum element without using an auxiliary stack
7. Implement two stacks in a single array
8. Recursive solution to sort a stack
9. Reverse a stack using recursion
10. Reverse a string using a stack data structure
11. Check if an expression is balanced or not
12. Find duplicate parenthesis in an expression
13. Evaluate a postfix expression
14. Decode a given sequence to construct a minimum number without repeated digits
15. Merging Overlapping Intervals
16. Convert an infix expression into a postfix expression
17. Find the next greater element for every element in a circular array
18. Find the next greater element for every array element
19. Find the previous smaller element for each array element
20. Reverse an array in C++
21. Longest Increasing Subsequence Problem
22. Find all elements in an array that are greater than all elements to their right
23. Iterative Implementation of Quicksort
24. Find all binary strings that can be formed from a wildcard pattern
25. Find the length of the longest balanced parenthesis in a string
26. Reverse text without reversing individual words
27. Reverse a string without using recursion
28. Inorder Tree Traversal
29. Preorder Tree Traversal
30. Postorder Tree Traversal
31. Check if two binary trees are identical or not
32. Find ancestors of a given node in a binary tree
33. Iteratively print the leaf to root path for every leaf node in a binary tree
34. Find preorder traversal of a binary tree from its inorder and postorder sequence
35. Construction of an expression tree
36. Print complete Binary Search Tree (BST) in increasing order
37. Depth First Search (DFS)
38. Check whether the leaf traversal of given binary trees is the same or not
39. Reverse level order traversal of a binary tree
40. Invert Binary Tree
41. Invert alternate levels of a perfect binary tree
42. Depth-First Search (DFS) vs Breadth-First Search (BFS)

Thanks for reading.