Stack Data Structure

DSA for Beginners
Learn more about Stack in DSA Self Paced Course
Practice Problems on Stack
Top Quizzes on Stack

What is Stack?

Stack is a linear data structure that follows a particular order in which the operations are performed. The order may be LIFO(Last In First Out) or FILO(First In Last Out). LIFO implies that the element that is inserted last, comes out first and FILO implies that the element that is inserted first, comes out last.

Stack Data Structure

There are many real-life examples of a stack. Consider an example of plates stacked over one another in the canteen. The plate which is at the top is the first one to be removed, i.e. the plate which has been placed at the bottommost position remains in the stack for the longest period of time. So, it can be simply seen to follow LIFO(Last In First Out)/FILO(First In Last Out) order.

Topics :

Introduction:

1. Introduction to Stack – Data Structure and Algorithm Tutorials
2. Applications, Advantages and Disadvantages of Stack
3. Implement a stack using singly linked list
4. Introduction to Monotonic Stack

Implementation of Stack in different languages:

1. Stack in C++ STL
2. Stack Class in Java
3. Stack in Python
4. Stack in C#
5. Implementation of Stack in JavaScript

Some other Implementation of Stack:

1. Implement Queue using Stacks
2. Design and Implement Special Stack Data Structure | Added Space Optimized Version
3. Implement two stacks in an array
4. Implement Stack using Queues
5. How to efficiently implement k stacks in a single array?
6. Design a stack that supports getMin() in O(1) time and O(1) extra space
7. Implement a stack using single queue
8. How to implement stack using priority queue or heap?
9. Create a customized data structure which evaluates functions in O(1)
10. Implement Stack and Queue using Deque

Standard problems on Stack:

• Easy:
  1. Infix to Postfix Conversion using Stack
  2. Prefix to Infix Conversion
  3. Prefix to Postfix Conversion
  4. Postfix to Prefix Conversion
  5. Postfix to Infix
  6. Convert Infix To Prefix Notation
  7. Check for balanced parentheses in an expression
  8. Arithmetic Expression Evalution
  9. Evaluation of Postfix Expression
  10. Reverse a stack using recursion
  11. Reverse individual words
  12. Reverse a string using stack
  13. Reversing a Queue
• Medium:
  1. How to create mergable stack?
  2. The Stock Span Problem
  3. Next Greater Element
  4. Next Greater Frequency Element
  5. Maximum product of indexes of next greater on left and right
  6. Iterative Tower of Hanoi
  7. Sort a stack using a temporary stack
  8. Reverse a stack without using extra space in O(n)
  9. Delete middle element of a stack
  10. Check if a queue can be sorted into another queue using a stack
  11. Check if an array is stack sortable
  12. Iterative Postorder Traversal | Set 1 (Using Two Stacks)
  13. Largest Rectangular Area in a Histogram | Set 2
  14. Find maximum of minimum for every window size in a given array
  15. Find index of closing bracket for a given opening bracket in an expression
  16. Find maximum difference between nearest left and right smaller elements
  17. Delete consecutive same words in a sequence
  18. Check mirror in n-ary tree
  19. Reverse a number using stack
  20. Reversing the first K elements of a Queue
• Hard:
  1. The Celebrity Problem
  2. Print next greater number of Q queries
  3. Iterative Postorder Traversal | Set 2 (Using One Stack)
  4. Print ancestors of a given binary tree node without recursion
  5. Length of the longest valid substring
  6. Expression contains redundant bracket or not
  7. Find if an expression has duplicate parenthesis or not
  8. Find next Smaller of next Greater in an array
  9. Iterative method to find ancestors of a given binary tree
  10. Stack Permutations (Check if an array is stack permutation of other)
  11. Spaghetti Stack
  12. Remove brackets from an algebraic string containing + and – operators
  13. Range Queries for Longest Correct Bracket Subsequence

Quick Links :

• ‘Practice Problems’ on Stack
• ‘Videos’ on Stack
• ‘Quizzes’ on Stack

Recomended:

• Learn Data Structure and Algorithms | DSA Tutorial
• Stack in Scala