Implement queue using stacks. 📍Join my paid Java DSA course here: https://www. * int pop() Removes the element from the front of the queue Oct 1, 2019 · Discussed how to implement queue using stacks with example. The implemented queue should support all the functions of a normal queue (`push`, `peek`, `pop`, and `empty`). Notes: You must use only standard operations of a stack – which means only push to top, peek/pop from top, size, and is empty operations are valid Implement Queue Using Two Stacks Problem Statement Given a sequence of enqueue and dequeue operations, return a result of their execution without using a queue implementation from a library. pop () -- Removes the element from in front of queue. At first, the concept of creating a queue with a stack was confusing. Learn efficient solutions in Python, TypeScript, and Java for your next interview. Implement the MyQueue Problem Highlights 🔗 Leetcode Link: Implement Queue using Stacks 💡 Problem Difficulty: Easy ⏰ Time to complete: 15 mins 🛠️ Topics: Stacks, Queues 🗒️ Similar Questions: Implement Stack using Queues 1: U-nderstand Understand what the interviewer is asking for by using test cases and questions about the problem. In this blog, we have discussed two approaches for implementing queue using two stacks: 1) Dequeue O(1) and Enqueue O(n) 2) Enqueue O(1) and Dequeue O(1). empty (): Checks if the queue is empty by verifying both the input and output stacks are empty. push (x) – Push element x to the back of queue. push(2); queue. We call these stacks input and output. Sep 10, 2025 · This post will implement a stack using the queue data structure. be/yu5txDlEs0cQueue Introduction: https://youtu. This implementation is scalable and highlights the importance of balancing operations between two stacks for efficiency. peek(); // returns 1 queue. Dec 15, 2022 · If the output stack is empty, it returns the precomputed peekEl. 2: Dequeue the element at the front of the queue. Define a class named QueueUsingStack. Shall we? Problem 1: Implement Stack using Queues Problem Link: LeetCode - Implement Stack using Queues Explanation: We need to implement a stack using only queue operations. Practice common problems: Familiarize yourself with classic stack and queue problems, such as valid parentheses, implement queue using stacks, and stack min/max. We are allowed to use only queue data structure. Now we are going to Learn to solve Questions on Queue in Data S Jul 23, 2025 · We are given a queue data structure, the task is to implement a stack using a single queue. int pop() Removes the element on the top of the stack and returns it. peek () – Get the front element. Established a set (2-3) of test cases to verify their own solution Implement a LIFO stack using two queues, supporting standard stack operations like push, pop, top, and empty, with constraints and follow-up challenges. Aug 11, 2023 · Steps for Implementing Stack Data Structure using two Queues To start with, we will create a class called Stack that will contain two queue objects — q1 and q2. Implement Stack using Queues in Python, Java, C++ and more. Intuitions, example walk through, and complexity analysis. Now we are going to Learn to solve Questions on Queue in Data S Can you solve this real interview question? Implement Queue using Stacks - Implement a first in first out (FIFO) queue using only two stacks. Established a set (2-3) of test cases to verify their own solution Dec 28, 2019 · Implementing a Queue using Stacks in JavaScript Continuing my series of writing blogs about things in JavaScript that are tricky to me initially, this is a blog explaining a simple way of building Problem Statement Implement a last-in-first-out (LIFO) stack using only two queues. * int pop() Removes the element from the front of the queue Leetcode 232. enQueue (q, x) 1) Push x to stack1 (assuming size of stacks is unlimited Can you solve this real interview question? Implement Queue using Stacks - Implement a first in first out (FIFO) queue using only two stacks. // Push an element x in the stack s This is a C++ Program to implement queue using stacks. * int pop() Removes the element from the front of the queue Can you solve this real interview question? Implement Stack using Queues - Implement a last-in-first-out (LIFO) stack using only two queues. Pop from the second stack if the second stack is not empty. It will briefly introduce the Queues and Stacks, and provide a suitable example that shows their implementation. You may simulate a stack by using a list or deque (double-ended queue), as long as you use only standard operations of a stack. Mar 7, 2024 · Using recursion, we can simulate a queue with a single stack for storage. When pushing an element, we'll add it to the This video has the Problem Statement, Solution Walk-through and Code for the Leetcode Question 232. C++ Program to Implement Queue Using Two Stacks This C++ Example implements a queue using two stacks (linked lists) where elements are pushed onto one stack and dequeued by transferring elements to another stack when needed: This article will discuss how to implement a Queue using a Stack in Java. Queue is open at both its ends. We add elements to the input stack, and when we want to remove an element, we move all the elements from the input stack to the output stack. The optimized approach ensures that each operation runs in amortized O (1) time. Simply push the elements into the first stack. Understand the approach, complexity, and implementation for interview preparation. Enqueue operation: 1. Implement the MyStack class: * void push(int x) Pushes element x to the top of the stack. Can you solve this real interview question? Implement Queue using Stacks - Implement a first in first out (FIFO) queue using only two stacks. This will reverse the order of the elements, effectively simulating a queue. This is a common interview question. Example 1: Implement the following operations of a queue using stacks. codingshuttl Oct 16, 2023 · Learn how to implement queue using stack in Data Structures. Sep 22, 2025 · A queue can be implemented using one stack and recursion. The implemented stack should support all the functions of a normal stack (push, top, pop, and empty). Jul 25, 2023 · Now we understand the basic principle of Stack and Queue. Check out TUF+:https://takeuforward. Jul 9, 2025 · Implement a first in first out (FIFO) queue using only two stacks. * int pop() Removes the element from the front of the queue Write a program to implement a stack using queues. This is the best Can you solve this real interview question? Implement Queue using Stacks - Implement a first in first out (FIFO) queue using only two stacks. Example: This example shows the implementation of Can you solve this real interview question? Implement Queue using Stacks - Implement a first in first out (FIFO) queue using only two stacks. We should use stack operations like push, pop, top, size, and isEmpty for implementing queue operations like enqueue, dequeue, and front. empty () -- Return whether the queue is empty. In this tutorial, we’ll explore implementing a queue using two stacks. Example: MyQueue queue = new MyQueue(); queue. n this method, in en-queue operation, the new element is entered at the top of stack1. Implement Queue using Stacks Implement a first in first out (FIFO) queue using only two stacks. A 3 days ago · This article explains how to implement a queue using stacks and how to implement a stack using queues. However, stacks follow Last-In-First-Out (LIFO) principle. * int pop() Removes the element from the front of the queue This is the video under the series of DATA STRUCTURE & ALGORITHM in a STACK & QUEUE Playlist. buym Learn how to solve the Implement a Queue Using Stacks coding problem to prepare for your next technical interview! LeetCode Solutions in C++23, Java, Python, MySQL, and TypeScript. In other words, design a stack that supports push and pop operations using standard enqueue and dequeue operations of the queue. Approach: We'll use two queues. Mar 15, 2014 · I've been going over some of the many coding interview questions. Implement Queue using Stacks - Explanation Problem Link Description You are given an array of characters which represents a string s. Problem Highlights 🔗 Leetcode Link: Implement Queue using Stacks 💡 Problem Difficulty: Easy ⏰ Time to complete: 15 mins 🛠️ Topics: Stacks, Queues 🗒️ Similar Questions: Implement Stack using Queues 1: U-nderstand Understand what the interviewer is asking for by using test cases and questions about the problem. Implement the MyQueue class: * void push(int x) Pushes element x to the back of the queue. empty () – Return whether the queue is empty. Queue is an abstract data structure similar to Stacks. * int pop() Removes the element on the top of the stack and 232. In-depth solution and explanation for LeetCode 225. Implementing a queue with stacks involves maintaining two stacks, where one stack is used to store the elements, while the other stack is used to reverse the order of the elements. This may seem While queues can be implemented directly using an array or a linked list, they can also be constructed using two stacks. The queue is a linear data structure that follows the First In First Out (FIFO) principle. In other words, design a queue that supports enqueue and dequeue operations using standard push and pop operations of the stack. push (x) -- Push element x to the back of queue. We previously explained and implemented several data structures in our data-structure-series; in this video, we implement the Queue data structure while making use of the built-in Stack classes function push () to push item in the stack. Sep 11, 2025 · This post will implement a queue using the stack data structure in C++, Java, and Python. Then process queries, where each query is one of the following types: 1 x: Enqueue element into the end of the queue. Feb 15, 2023 · How To Implement A Queue With 2 Stacks You read it right! We will be using two stacks or 2 arrays to mimic a queue sequence. One end is always used to insert data (enqueue) and the other is used to remove data (dequeue). Sep 28, 2022 · Implement a first in first out (FIFO) queue using only two stacks. org/plus?source=youtubeFind DSA, LLD, OOPs, Core Subjects, 1000+ Premium Questions company wise, Aptitude, SQL, AI doubt Apr 16, 2024 · Welcome to our algorithm tutorial on implementing a queue using stacks! Whether you're a coding enthusiast or a programmer seeking solutions to algorithmic challenges, this tutorial is tailored to provide you with a clear understanding of how to implement a queue using stacks. Feb 11, 2019 · Complexities n is the total items between the 2 stacks (in the overarching queue) Time: O ( 1 ) - amortized (for enqueue and dequeue operations) Amortized time is the way to express the time Sep 6, 2019 · One form is via the question, “How do you implement a queue using two stacks?” Before getting to the solution, we need a quick review of stacks and queues (and for a more in-depth explanation Implement a queue using one or two stacks. By using two stacks, we can simulate the FIFO behavior of a queue while maintaining the LIFO nature of stacks. A queue follows First-In-First-Out (FIFO) principle, meaning elements are removed in the same order they were added. push(1); queue. I have written a C program for implementation of queue using stacksDSA Full Course: https: https: Nov 27, 2024 · How to implement a queue with a stack (more precisely: with two stacks)? Tutorial with illustrations and Java code examples. The implemented queue should support all the functions of a normal queue (push, peek, pop, Implement a first in first out (FIFO) queue using only two stacks. Among the myriad of data structures available, the queue stands out for its ability to maintain order — a necessity for tasks like scheduling, buffering, and more. The first method assumes Enqueue operation to be costly and second method assumes dequeue operation to be costly. But this is really two stacks, because the system program counter is a stack. 6K subscribers Subscribed Oct 26, 2021 · Hey guys, In this video, We're going to solve two very important problems on Stacks and Queues. Implement Queue using Stacks (LeetCode 232) | Side by side demo and diagrams Nikhil Lohia 62. 2. The two-stack method transfers elements; the one-stack method uses recursion. * int pop() Removes the element from the front of the queue Apr 1, 2025 · Efficient data management is at the heart of computer programming. In de-queue operation, if stack2 is empty then all the elements are moved to stack2 and finally top of stack2 is returned. function pop () to pop out an item from the stack. We can then remove an element from the output stack. The implemented queue should support all the functions of a normal queue (push, peek, pop, and empty). be/fuqHpjsxhbUGFG link: https://www. Sep 17, 2023 · 232. empty(); // returns May 11, 2023 · Here is an implementation of a queue data structure using a stack in C programming language with step-by-step instructions and an algorithmic approach. * int pop() Removes the element from the front of the queue Suppose we have two stacks and no other temporary variable. In this article, we will use a Queue data structure to implement the stack operations that follow the LIFO (Last In, First Out) principle. * int pop() Removes the element from the front of the queue May 29, 2025 · Implementing a Queue Using Two Stacks in Java When learning about data structures, stacks and queues are often introduced early on. Implement the MyStack class: void push(int x) Pushes element x to the top of the stack. peek () -- Get the front element. You must do this by modifying the input array in-place with O(1) extra memory. For deque operation Can you solve this real interview question? Implement Queue using Stacks - Implement a first in first out (FIFO) queue using only two stacks. Is to possible to "construct" a queue data structure using only the two stacks? Can you solve this real interview question? Implement Queue using Stacks - Implement a first in first out (FIFO) queue using only two stacks. org/queue-using-stacks/Ti Jul 23, 2025 · Using two stacks: We can simulate a queue using two stacks. The main challenge is that queues follow FIFO, while stacks follow LIFO. Queue is a particular kind of abstract data type or collection in which the entities in the collection are kept in order and the principal (or only) operations on the collection are the addition of entities to the rear terminal position, known as enqueue, and removal of entities from the front terminal position, known as dequeue Aug 5, 2025 · Using one Queue In this approach, we will create a class and we will write the essential methods for implementation of the stack. Jan 14, 2024 · Implement a first in first out (FIFO) queue using only two stacks. We must use queue operations like enqueue, dequeue, front, size to implement stack operations like push, pop, and top. Jul 19, 2016 · Implement a first in first out (FIFO) queue using only two stacks. In this challenge, you must first implement a queue using two stacks. In this tutorial, we'll delve into the concept of a queue and stacks, elucidating their differences and how they can Implement Queue using StacksImplement Queue using Two StacksLeetcode 232 - Leetcode EasyTopics Covered: Stacks, QueuesPythonBuy Me a Coffee: https://www. Implement Queue using Stacks - Implement a first in first out (FIFO) queue using only two stacks. Implement Queue using Stacks 232. During deQueue, if the storage stack has more than one element, we use recursion to store the popped item temporarily and push it back after we reach the base case. Discover an efficient solution with clear explanations and interactive visualization of how stack operations can simulate queue behavior. Better than official and forum solutions. You need to implement a queue data structure using only two stacks. Your MyQueue class must support these four operations: Oct 15, 2024 · A queue operates in a First-In-First-Out (FIFO) manner, while a stack works as a Last-In-First-Out (LIFO). Jan 8, 2025 · Learn how to implement a queue using two stacks in Python for LeetCode 232, that tests your understanding of data structures. we will going to build each method by crating a queue at first. - `int pop()` Removes the element from the front of the queue and returns it Jul 23, 2025 · In Python, lists can be used to implement a variety of data structures, including stacks and queues. Mar 11, 2024 · Master LeetCode's queue with stacks problem with our expert guide. I was wondering how you would go about implementing a queue using two stacks in Python? Python is not my strongest language so I ne Dequeue: remove the element from the front of the queue and return it. Stacks operate on a Last-In-First-Out (LIFO) principle, while … This is a Java Program to implement a queue using two stacks. Stack is a linear data structure that can be implemented using many other data structures like array and linked list. Algorithm: We can implement queue using stack using the below algorithm Initialize 2 empty stacks s1 and s2 For enqueue operation push the element to the top of the stack s1. Consider real-world applications: Be ready to discuss practical use cases of stacks and queues in software systems. Implement Queue using Stacks Table of contents Description Solutions Solution 1: Double Stack Implement a first in first out (FIFO) queue using only two stacks. For instance, a common question involves implementing a queue using two stacks. 232. The problem statement here is to implement a queue using a stack. Detailed solution for LeetCode Implement Queue using Stacks in C++. Stack Introduction: https://youtu. the first element added to the queue is the first one to be removed and the last element added to the stack is the first one to be removed. Write a program to implement queue using stack. Implement Queue using Stacks, with Time Complexity of O (n Mar 15, 2019 · This lecture explains two methods to implement queue using stacks only. Conclusion Using two stacks allows us to implement a queue with all its operations while adhering to the constraints of using only stack operations. In this article, we explore how to simulate a queue using two stacks — a classic programming challenge — and how to implement an interactive system in PHP to . Implement Queue using Stacks: Step-by-Step Approach LeetCode - The World's Leading Online Programming Learning Platform Level up your coding skills and quickly land a job. Dequeue operation: 1. The recursion stack implicitly becomes the second stack. geeksforgeeks. You may assume that all operations are valid (for example, no pop or peek operations will be called on an empty queue). Oct 28, 2023 · Implement the following operations of a queue using stacks. * int pop() Removes the element from the front of the queue Struggling with "Implement Queue Using Stacks" on Leetcode? 🤔 In this video, we break it down step-by-step using two stacks to efficiently implement a queue with amortized O (1) complexity for Oct 10, 2024 · Now that we've refreshed our memories, let's go over some problems. For implementing queue using stack, one method is to make dequeue costly and other is to make enqueue costly C Program to Implement Queue using Two Stacks This is a C program to implement queue using two stacks. May 18, 2023 · In coding interviews, you may be challenged to implement one data structure using another. The recursion uses the call stack to temporarily hold elements while accessing the bottom element of the stack, which represents the front of the queue. Sep 18, 2012 · You can "cheat" by using recursive function calls to pop the stack, then you push the item being queued, then as the recursive calls unwind you push what was popped. Oct 7, 2024 · In this approach to implement queue using stack, we are making the dequeue operation of one stack costly for reaching the functionality of a queue. In this article, we’ll explore how to use Python lists to create and perform basic operations on stacks and queues. Let’s see how we can implement Queue using Stack. * int pop() Removes the element from the front of the queue Implement queue using stack | GeeksforGeeks GeeksforGeeks 942K subscribers Subscribed Algorithm A queue can be implemented using two stacks, there are two ways to implement a queue using stacks, first by making enqueue operation costly and second by making dequeue operation costly. stack and queue are opposite that's why for FIFO and LIFO conditions we are adding some conditional statements. pop () – Removes the element from in front of queue. Using List as Stack in Python A stack is a fundamental data structure that follows the Last In, First Out (LIFO) principle. * int pop() Removes the element from the front of the queue Sep 18, 2025 · Implement a stack using queues. as stack has pop, push, peek methods. * int pop() Removes the element from the front of the queue Implement Queue using Stacks - Leetcode 232 - Python NeetCodeIO 304K subscribers Subscribe Aug 24, 2024 · Implement a first in first out (FIFO) queue using only two stacks. Implement the `MyQueue` class: - `void push(int x)` Pushes element `x` to the back of the queue. Write a function which reverses a string. Using two queues: We can Nov 23, 2021 · Implement Stack using Queues - Leetcode 225 - Python NeetCode 1M subscribers Subscribe Jul 23, 2025 · Approach We need two Stack to implement the queue because the Queue is First In First Out (FIFO) data structure and the Stack is Last In, First Out (FIFO) i. Use two stacks to implement queue. Oct 22, 2024 · To implement a queue using stacks, use two stacks: one for enqueue operations and another for dequeue, ensuring FIFO behavior by reversing order during dequeue. Also Read: Stack using two queues The idea is to keep the newly inserted element always at the front of the queue, preserving the order of previous elements by appending the new element at the back and rotating the queue by size n so that the new item is at the front. It also provides code examples in Java, Python, Go, JavaScript, and C++. e. pop(); // returns 1 queue. 24eroggxwayvnvftwp0akofguwmgxeuz9sz46mni9dztvfh