With this approach, we employ the first pointer, labeled as next to traverse the array, while the second pointer, labeled as current serves the crucial role of identifying the position where Sep 18, 2025 · The Two Pointers technique is a more general pattern that applies to a wider range of problems, including linked lists (e. The key idea is that the pointers start at different positions and move in a coordinated way to traverse the data structure efficiently. Jul 23, 2025 · The two-pointer technique is a common technique used in linked list problems to solve a variety of problems efficiently. Aug 13, 2022 · The Two Pointers Technique is a technique that allows you to optimize your runtime (time complexity and often space complexity) By utilizing some ordering data. This is something which you’ll recognize instantly after solving some questions on it, s code template for solving a 2 pointer approach. These patterns solve 90% of linked list interview questions in O (1) space! Dive deep into the Two Pointer technique, a fundamental algorithm pattern that optimizes solutions for array, string, and linked list problems. May 2, 2020 · If you are learning about linked lists, it's time to check out the Two Pointer technique! Let's tackle this algorithm using a LeetCode problem: Given a non empty linked list, return the middle Aug 6, 2024 · Time Complexity: O (N), where N is the number of nodes in the Linked List. Here are all of the method Oct 1, 2024 · Among the various techniques to optimize code performance, the “ two pointers” technique stands out as a powerful tool, especially when working with arrays and lists. More on Lists: The list data type has some more methods. This is best demonstrated with an example and probably the most famous example of this technique is cycle detection. Aug 3, 2022 · One of the algorithms or techniques widely used for both array and linked list problems is the “two-pointer technique”. The fast and slow pointer (also known as the tortoise and hare approach) is quite a famous two-pointer technique used to determine properties about directed data structures: an array, a single-linked list, or a graph all be used. Jan 26, 2025 · In this video, I talk about the two pointers technique which is a very important DSA topic for coding interviews. 42K subscribers Subscribe Jun 11, 2025 · The Two Pointers Technique is a widely used algorithmic paradigm in computer science, employed to solve a variety of problems involving arrays, linked lists, and other data structures. Jul 9, 2015 · The two code examples below both add a node at the top of a linked list. As the name suggests, one pointer (the “fast” pointer) moves faster than the other (the “slow” pointer). Jul 23, 2025 · Conclusion The two-pointer approach is a valuable tool in the programmer, offering a versatile and efficient technique for solving array-related problems. The differences between how the pointers iterate can be used to make calculations on the list more efficient. Feb 17, 2024 · Usage: The two pointer technique is a powerful strategy employed in algorithmic problem-solving, particularly in scenarios where the data is linear, such as arrays, strings, or linked lists. There are a range of different variations of this that can be applied to Jul 11, 2023 · The two pointer technique is a flexible and versatile strategy that can be applied to various scenarios, such as finding pairs in a sorted array, checking for a palindrome, or finding a cycle in a linked list. This approach works in constant space. This approach uses two pointers that traverse the list, one Jan 21, 2023 · One of these approaches goes by Two-Pointers and is the subject of this video. Mar 7, 2022 · Let's start with a classic problem:Given a linked list, determine if it has a cycle in it. Jan 20, 2025 · The two-pointer traversal technique is a powerful and efficient method for solving common problems in linked lists. * Key Concept: Two-pointer technique on linked lists * Time Complexity: O (n + m) #LeetCode #DSA #Java #LinkedList #ProblemSolving #CodingJourney 7 57 Posts Day 1 of my dsa journey 📌 Topic: Linked List Today I officially started my 100 Days of DSA Challenge, and I’m beginning with one of the most important data structures — Linked List. The approach has 3 steps: Initialization: Starting points. Many algorithms just use a single pointer to attain or keep track of a single element: Mar 20, 2022 · #TechnologyStrive #DSA #LinkedListMiddle Element of a Linked List This video covers both naïve solution and optimized solution to find middle element of a li The fast and slow pointers technique involves using two pointers that traverse a linked list at different speeds. Learn Solved a classic Linked List problem that involves recursion and merging logic 🚀 GeeksforGeeks: Flattening a Linked List :https://lnkd. 4 days ago · Among the many cycle-detection techniques, **Floyd's Cycle-Finding Algorithm** (also known as the "Tortoise and Hare Algorithm") stands out for its elegance and efficiency. Feb 9, 2023 · The Two Pointer approach is a technique used in linked list algorithms to traverse the list and manipulate its elements efficiently. Sep 6, 2023 · The two-pointer technique is a fundamental algorithmic approach that plays a pivotal role in optimizing solutions to specific types of problems in computer science. Apr 17, 2021 · Two are better than one if they act as one. Imagine there are two runners with different speed. Learn its variations with practical, runnable code examples in Python. A very useful technique for dealing with linked lists involves iterating through the list with 2 or more pointers. Dec 19, 2025 · This article compiles all classic Linked List two-pointer algorithm problems on LeetCode, including detailed explanations by Labuladong and algorithm visualizations. LeetCode Problems solved in this video: Thanks for Watching! If you found this video helpful, check other Geekific DSArevision. Sep 27, 2023 · Mastering the Two-Pointer Algorithm: A Guide When it comes to solving complex problems involving arrays, linked lists, or even strings, the Two-Pointer Algorithm emerges as a powerful technique. The runner technique, also known as the two-pointer technique, is a popular method used in linked list problems. This approach optimizes the runtime by utilizing some order (not necessarily sorting) of the data. This method is highly efficient when traversing arrays Jan 21, 2023 · One of these approaches goes by Two-Pointers and is the subject of this video. , cycle detection), in-place array modifications, and palindrome checks. By utilizing two pointers that move through the . Approach: • Use the two-pointer technique to traverse both interval lists simultaneously. It involves using two pointers or indices to make the solution faster and use less memory. With this approach, we employ the first pointer, labeled as next to traverse the array, while the second pointer, labeled as current serves the crucial role of identifying the position where Jan 7, 2024 · In essence, the Two Pointer technique aims to address problems where identifying pairs, subarrays, or specific patterns within arrays or linked lists is crucial. The Two Pointers technique is a useful way to solve problems, especially with arrays or linked lists. Oct 18, 2021 · Once the two pointers are a distance of n apart in the linked list, they move at the same pace until the second pointer reaches the tail. Jun 13, 2021 · I am trying to understand the following implementation for returning the nth last node in a linked list: const nthLastNode = (linkedList, n) => { let current = null; let tailSeeker = linkedL May 2, 2020 · If you are learning about linked lists, it's time to check out the Two Pointer technique! Let's tackle this algorithm using a LeetCode problem: Given a non empty linked list, return the middle Feb 28, 2024 · How do we handle two pointers in a linked list? This question might seem daunting at first, but with the right strategies and understanding, mastering it can After this card, you will: Understand the structure of singly linked list and doubly linked list; Implement traversal, insertion, deletion in a singly or doubly linked list; Analyze the complexity of different operations in a singly or doubly linked list; Use two-pointer technique (fast-pointer-slow-pointer technique) in the linked list; "Two-Pointers-with-Himel" repository offers implementations and explanations of the Two Pointer Technique, a powerful algorithmic approach for efficient problem-solving in arrays and linked lists. ---This video is based on the question The runner technique in linked lists involves using two pointers moving at different speeds to traverse the list. Elevate your coding skills and tackle diverse challenges with ease Level up your coding skills and quickly land a job. This blog summarizes key LeetCode problems where the two-pointer method not only simplifies the approach but also optimizes performance, especially compared to brute-force solutions. If they are running on a straight path, the fast In this case, an advantage of using a binary tree is significantly reduced because it is essentially a linked list which time complexity is O (n) (n as the number of nodes and 'O ()' being the Big O notation) and it has more data space than the linked list due to two pointers per node, while the complexity of O (log2 n) for data search in a LeetCode Explore is the best place for everyone to start practicing and learning on LeetCode. Supported languages: Java, C++, Python, Golang, and JavaScript. In linked lists, the Two-Pointer Technique is commonly used to detect cycles or to find the middle element. This technique is an easy and efficient way to improve the performance of our algorithm. For example, one pointer can move one step at a time while the other moves two steps. Whether it is searching, manipulation, optimization, or comparison, the two-pointer approach excels in various problem-solving scenarios. No matter if you are a beginner or a master, there are always new topics waiting for you to explore. In this chapter, we will start with how to reverse a singly linked list and explore more classic problems. 2 days ago · This chapter describes some things you’ve learned about already in more detail, and adds some new things as well. Overview In this tutorial, we’ll discuss the two-pointer approach for solving problems involving arrays and lists. This approach is generally used to search pairs in a sorted array. Mar 22, 2017 · Ten years ago, I was shown a technique for traversing a linked list: instead of using a single pointer, you used a double pointer (pointer-to-pointer). Discover how to effectively use the `two pointers technique` to find the middle of a linked list in this concise guide. You might have come up with the solution using the hash table. And that is pointers, double pointers and how to use them effectively with linked data structures. Jul 11, 2023 · The two pointer technique is a flexible and versatile strategy that can be applied to various scenarios, such as finding pairs in a sorted array, checking for a palindrome, or finding a cycle in a linked list. Master two patterns: slow-fast (different speeds) and gap (same speed, different start). This technique involves using two pointers, which are essentially indices or references that traverse the data structure in a coordinated manner. If they are running on a straight path, the fast We have explained Fast and slow pointer technique in Linked List which is also known as tortoise and hare algorithm. Linked List Cycle, Two Pointers Technique, Python, Linked List NeedCode⚡ 1. Feb 8, 2024 · The two-pointer technique is a pattern where two pointers iterate over the data structure in together or separately until they satisfy a certain condition. It uses two pointers moving at different speeds: a "slow" pointer (tortoise) that advances 1 step at a time and a "fast" pointer (hare) that advances 2 steps at a time. Detect Cycle in Linked List Let's use the problem Feb 2, 2025 · The two-pointer approach is another elegant and efficient technique often used in algorithm design, especially when working with arrays or lists. But what is a pointer? It's a variable that represents an index or position within a data structure, like an array or linked list. Find the nth node from the end of the linked list in java using length and two pointers with algorithm, input output, and programs. The name does justice in this case, it involves using two pointers to save time and space. This strategy involves the use Feb 9, 2023 · By leveraging the sorted nature of the array, we can implement the two-pointer approach, a technique that utilizes two pointers to streamline the process. Instead of relying on brute-force Learn the two-pointer technique with examples. Learn how to solve array, linked list, and string problems efficiently using this powerful algorithm. The technique yielded smaller, more elegant 4 days ago · Array study guide for coding interviews, including practice questions, techniques, time complexity, and recommended resources Apr 4, 2024 · The two-pointer technique is a widely used approach to solving problems efficiently, particularly scenarios involving arrays or linked lists. Feb 9, 2023 · By leveraging the sorted nature of the array, we can implement the two-pointer approach, a technique that utilizes two pointers to streamline the process. Mar 28, 2025 · The two-pointer approach is a powerful technique used in solving problems efficiently when working with sorted data structures like arrays or linked lists. By using two pointers moving at different speeds, we can achieve significant Feb 11, 2024 · A comprehensive guide to the Two Pointer Approach! Explore its benefits, types, problem-spotting tips, and real-world examples for mastering this versatile strategy. The two-pointer technique is a versatile and efficient strategy commonly used in solving problems on arrays, strings, linked lists, and other data structures. It involves initializing two pointers, comparing their sum to the target, and adjusting the pointers May 5, 2025 · This is a classic problem that tests your understanding of two-pointer technique – a must-know for interviews! 👨‍💻🔥 Swipe ️ to see how the red node (value 4) gets removed from the list 👇 * Key Concept: Two-pointer technique on linked lists * Time Complexity: O (n + m) #LeetCode #DSA #Java #LinkedList #ProblemSolving #CodingJourney 7 57 Posts This problem helped me strengthen my understanding of: 🎯 Linked List manipulation 🎯 Two-pointer technique 🎯 Space optimization Always learning, always growing! 💪 2 12 Posts The key detail is that intersection is based on node reference, not just value. Here is the actual code, with pseudocode as comments: Mar 7, 2022 · Let's start with a classic problem:Given a linked list, determine if it has a cycle in it. Two pointers are THE fundamental technique for linked list problems. An intersection exists if two intervals overlap, and the overlapping part should be added to the result. Jan 7, 2024 · In essence, the Two Pointer technique aims to address problems where identifying pairs, subarrays, or specific patterns within arrays or linked lists is crucial. Explore Python code examples, detailed problem analyses, and contributions to enhance your understanding and mastery of this technique. There are a range of different variations of this that can be applied to Mar 17, 2025 · The two-pointer technique uses two-pointers or variables to iterate through a data structure, typically an array or linked list. It is used to efficiently solve several problems by using two pointers. com e middle, eg: middle element of the linked list. g. Let’s get started. Apr 4, 2024 · The two-pointer technique is a widely used approach to solving problems efficiently, particularly scenarios involving arrays or linked lists. Table of contents Given problem Solution of Two pointers technique When to use Wrapping up Given problem Given a sorted array nums, remove the duplicates in-place such that each element appear only once and return the new The Two Pointers Technique is a problem-solving strategy where we use two variables (pointers) to traverse an array, string or linked list from different directions or at different speeds. By using two pointers that traverse data structures in a coordinated manner, we can reduce time complexity from O (n²) to O (n) in many cases. It’s generally applied on arrays and linked lists. This is the best place to expand your knowledge and get prepared for your next interview. In this technique pointers represent either index Jun 6, 2013 · The linked list with a loop problem is classical - "how do you detect that a linked list has a loop" ? The "creative" solution to this is to use 2 pointers, one moving at a speed of 1 and the second one at the speed of 2. By using two pointers moving at different speeds, we can achieve significant In the last chapter, we have introduced how to use the two-pointer technique in a linked list. The Two-Pointer Technique efficiently solves the "Two Sum Sorted" problem in a sorted array. Jul 23, 2025 · Unlock efficient array and linked list traversal with the Two Pointers Technique! Master this essential algorithm for faster, cleaner code. 🧠 Approach: I used the elegant two-pointer switching technique: • Initialize two pointers, one for each list. Detect Cycle in Linked List Let's use the problem The two-pointer technique is a versatile and efficient strategy commonly used in solving problems on arrays, strings, linked lists, and other data structures. It involves using two pointers that traverse the linked list at different speeds or in different directions. more A very useful technique for dealing with linked lists involves iterating through the list with 2 or more pointers. This technique uses two pointers that either move towards each other, away from each other, or in a synchronous manner, to scan the array or list in one or two passes. Try to think it over by yourself before reading the remaining content. But there is a more efficient solution using the two-pointer technique. The runner technique in linked lists involves using two pointers moving at different speeds to traverse the list. We move from the left and right with different cond The questions linked here use the two-pointer technique to eliminate unnecessary pairs from the search, producing O(n) solutions compared to the O (n 2) brute-force solutions. When to use the The two-pointer technique is a search algorithm used to solve problems involving collections such as arrays and lists by comparing elements pointed by two pointers and updating them accordingly. This method is highly efficient when traversing arrays Dec 18, 2019 · Two pointer approach is an essential part of a programmer’s toolkit, especially in technical interviews. Jan 10, 2026 · 🚀 Ultimate Linked List Master List for Amazon SDE-1 Prep (Deduplicated & Grouped Logically) Hey LeetCoders! 👋 If you're grinding for Amazon SDE-1 (or any FAANG-level role), Linked Lists are a staple in interviews—especially for pointer manipulation, cycles, and re-linking problems. The Two Pointers pattern is a common algorithmic technique used primarily to simplify problems that involve arrays or linked lists. Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube. Feb 5, 2020 · In this article, we will learn about two pointer technique. But whereas the first code example uses a double pointer the second code example uses a single pointer code example 1: str The Two Pointer technique is a powerful algorithmic approach that optimizes the way we traverse data structures, making solutions faster and more efficient. It involves initializing two pointers, comparing their sum to the target, and adjusting the pointers Sep 15, 2025 · The Two-Pointers Technique is a simple yet powerful strategy where you use two indices (pointers) that traverse a data structure—such as an array, list, or string—either toward each other or in the same direction to solve problems more efficiently Learn about how the most common singly linked list problems can be solved by iterating with two-pointers. Apr 4, 2025 · 1. LeetCode Problems solved in this video: Thanks for Watching! If you found this video helpful, check other Geekific Feb 9, 2023 · The Two Pointer approach is a technique used in linked list algorithms to traverse the list and manipulate its elements efficiently. Introduction to Two Pointers Intuition As the name implies, a two-pointer pattern refers to an algorithm that utilizes two pointers. Detect Cycle in Linked List Let's use the problem The Two Pointer Technique is a powerful algorithmic strategy used to solve problems involving arrays, strings, or linked lists efficiently. This approach uses two pointers that traverse the list, one The two-pointer technique is a search algorithm used to solve problems involving collections such as arrays and lists by comparing elements pointed by two pointers and updating them accordingly. in/g29sgfuf 📌 Problem Summary Given a linked list where 4 days ago · Among the many cycle-detection techniques, **Floyd's Cycle-Finding Algorithm** (also known as the "Tortoise and Hare Algorithm") stands out for its elegance and efficiency. Let’s head onto Coding Ninjas Studio and try to code for this problem. Oct 9, 2021 · Leetcode 141. Technique Description In many problems involving arrays or lists, we have to analyze each element of the array compared to its other The Two Pointers pattern is a common algorithmic technique used primarily to simplify problems that involve arrays or linked lists. In this video, I go over a topic I find many students struggle with. Two pointer algorithm is one of the most commonly asked questions in any programming interview. Pointers can be at any place depending upon what we are trying to achieve. 2.

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