Master the most asked Stack Coding Questions with this complete list of beginner to advanced problems. Perfect for coding interviews and placements.
Stack interview questions are among the most frequently asked problems in coding interviews, especially for product-based companies and FAANG roles. A stack follows the LIFO (Last In, First Out) principle and is heavily used in real-world applications such as expression evaluation, undo-redo operations, browser history navigation, recursion handling, and memory management. Because of this wide usage, interviewers rely on stack problems to test a candidate’s problem-solving ability, logical thinking, and understanding of data structure fundamentals.
This guide provides a complete and carefully curated list of the most asked stack coding interview questions, covering everything from basic stack operations to advanced real-world problem patterns. You will start with foundational concepts like stack implementation using arrays and linked lists, push and pop operations, and time complexity analysis. As you progress, the article dives deep into popular interview problems such as valid parentheses, infix to postfix conversion, expression evaluation, and stack-based string manipulation.
A major focus of this guide is monotonic stack problems, which are extremely important for technical interviews. Questions like Next Greater Element, Stock Span Problem, Daily Temperatures, Largest Rectangle in Histogram, and Trapping Rain Water are explained as core stack patterns that appear repeatedly across interviews. Mastering these patterns can help you solve multiple variations of problems efficiently and confidently.
The article also includes advanced design-based stack questions such as Min Stack, Max Stack, stack with getMin in O(1), stack using queues, and queue using stacks. These problems are commonly asked to evaluate your understanding of data structure optimization and real-world system design. Additionally, recursion-based stack problems and matrix-based stack applications are covered to ensure you are fully prepared for any level of interview difficulty.
Whether you are a beginner preparing for your first coding interview or an experienced developer targeting FAANG and top product-based companies, this in-depth stack interview question guide will help you build strong fundamentals, recognize common patterns, and approach interviews with confidence. Practice these problems thoroughly, understand the logic behind each solution, and you will significantly increase your chances of cracking coding interviews.
BASIC STACK QUESTIONS (Must-Know)
- What is a Stack? Explain LIFO principle
- Stack implementation using array
- Stack implementation using linked list
- Push, Pop, Peek operations
- Check if stack is empty or full
- Time & space complexity of stack operations
- Difference between stack and queue
- Applications of stack in real life
EXPRESSION & STRING PROBLEMS
- Reverse a string using stack
- Check for balanced parentheses
- Valid parentheses problem
- Check redundant brackets
- Infix to postfix conversion
- Infix to prefix conversion
- Postfix expression evaluation
- Prefix expression evaluation
- Longest valid parentheses
- Minimum add to make parentheses valid
- Score of parentheses
STACK WITH ARRAY / LINKED LIST
- Implement stack using linked list
- Implement two stacks in one array
- Implement k stacks in one array
- Stack using dynamic array (resize)
STACK USING STACK / QUEUE (FAVORITE)
- Implement stack using queue
- Implement stack using two queues
- Implement stack using one queue
- Implement queue using stack
- Implement queue using two stacks
MONOTONIC STACK
- Next Greater Element (NGE)
- Next Smaller Element
- Previous Greater Element
- Previous Smaller Element
- Next Greater Element II (circular array)
- Daily Temperatures
- Stock Span Problem
- Online Stock Span
- Asteroid Collision
- Remove K Digits
- Trapping Rain Water (using stack)
- Largest Rectangle in Histogram
MATRIX + STACK QUESTIONS
- Maximal Rectangle in Binary Matrix
- Largest Rectangle of 1s in Matrix
- Sum of subarray minimums
- Sum of subarray ranges
RECURSION + STACK
- Reverse a stack using recursion
- Sort a stack using recursion
- Delete middle element of stack
- Insert element at bottom of stack
- Check stack is palindrome
ADVANCED / DESIGN STACK QUESTIONS
- Design Min Stack
- Design Max Stack
- Design stack with getMin() in O(1)
- Design stack with getMiddle() in O(1)
- Design browser back-forward system
- Design undo-redo functionality
- Design stack supporting increment operation
- Frequency Stack (LeetCode 895)
HARD INTERVIEW QUESTIONS
- Simplify Unix Path
- Decode String
- Basic Calculator I / II / III
- Remove duplicate letters
- Validate stack sequences
- Exclusive time of functions
- Car Fleet
- Maximum Width Ramp
- Smallest Subsequence of Distinct Characters
TOP COMPANY FAVORITES
| Company | Frequently Asked |
|---|---|
| Amazon | Valid Parentheses, Min Stack, Histogram |
| Calculator, Decode String | |
| Microsoft | NGE, Stock Span |
| Remove K Digits | |
| Uber | Car Fleet |
| Adobe | Infix/Postfix |
| Paytm | Stack using Queue |
MUST-DO TOP 15 (If Time Is Less)
- Valid Parentheses
- Next Greater Element
- Stock Span
- Largest Rectangle in Histogram
- Trapping Rain Water
- Min Stack
- Infix → Postfix
- Reverse Stack
- Sort Stack
- Stack using Queue
- Daily Temperatures
- Remove K Digits
- Decode String
- Basic Calculator
- Maximal Rectangle
FAQ : Stack Coding Questions and Tricks
1. What is a stack in data structures?
A stack is a linear data structure that follows the Last In, First Out rule. The last element added to the stack is the first one removed.
2. Why are stack questions so common in coding interviews?
Stack questions test logical thinking, problem-solving skills, and understanding of core data structure concepts. They are also used in many real-world applications like undo-redo and expression evaluation.
3. What are the basic operations performed on a stack?
The basic operations are push (add an element), pop (remove an element), peek or top (view the top element), and checking if the stack is empty or full.
4. What is the difference between a stack and a queue?
A stack follows LIFO order, while a queue follows FIFO order. In a queue, the first element added is the first one removed.
5. Which stack problems are most frequently asked in interviews?
Common stack interview questions include valid parentheses, next greater element, stock span problem, largest rectangle in histogram, and min stack.
6. What is a monotonic stack and why is it important?
A monotonic stack keeps elements in increasing or decreasing order. It is important because it helps solve many interview problems efficiently, such as next greater or smaller element.
7. How is stack used in real-world applications?
Stacks are used in browser navigation, undo-redo features, recursion, expression evaluation, syntax checking, and memory management.
8. What is a Min Stack and why is it asked so often?
A Min Stack is a special stack that returns the minimum element in constant time. It is asked to test optimization skills and understanding of auxiliary data structures.
9. Can a stack be implemented using a queue?
Yes, a stack can be implemented using one or two queues. This question checks understanding of how data structures can be transformed.
10. Is recursion related to stack?
Yes, recursion internally uses a call stack to store function calls, local variables, and return addresses.
11. How should beginners prepare for stack interview questions?
Beginners should start with basic stack operations, then practice classic problems like valid parentheses, next greater element, and stock span.
12. Are stack problems important for FAANG interviews?
Yes, stack problems are very important for FAANG and product-based companies because they appear frequently and are used to test core fundamentals.
You can also read : Linked List Coding Questions
Mr. Raj Kumar is a highly experienced Technical Content Engineer with 7 years of dedicated expertise in the intricate field of embedded systems. At Embedded Prep, Raj is at the forefront of creating and curating high-quality technical content designed to educate and empower aspiring and seasoned professionals in the embedded domain.
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