When To Use Two Pointer Approach. By understanding its applications and knowing when to use it, program

By understanding its applications and knowing when to use it, programmers can leverage the two-pointer approach to write elegant and efficient algorithms that tackle a wide range of array-related challenges. By utilizing two pointers either moving towards each other or in the same direction, we can reduce the time complexity of many problems from O (n2) to O (n) or O (nlog⁡n). By using this approach we are able to complete this problem efficiently, in O(n) time (we must iterate through the entire list once) and O(1) space complexity (we always use only three variables no matter what size the list is: two pointers and a counter). Nov 16, 2024 · The Two Pointers technique is a highly efficient approach often used to solve problems that involve arrays or linked lists. In this post, you will be going through 13 problems which kind of sets the tone for the other Aug 10, 2024 · This approach involves two pointers starting from opposite ends of the data structure and moving toward each other, meaning the pointers move in opposite directions. Oct 18, 2021 · In this article, and as a part of my own knowledge-building, I have attempted to explain how a certain type of search algorithm can be written using the two-pointer approach. 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. It will cover the theory behind the approach, provide step-by-step examples, and discuss its time and space complexity. This technique is useful when we need to find unique elements in a sorted array. Level up your coding skills and quickly land a job. Jul 23, 2025 · Two pointers is really an easy and effective technique which is typically used for searching pairs in a sorted array. It uses two pointers to traverse data in tandem, reducing unnecessary computations. Apr 4, 2024 · The two-pointer technique is a widely used approach to solving problems efficiently, particularly scenarios involving arrays or linked lists. Now, that you are familiar with the basics of arrays from the last class, Manvi Jul 26, 2023 · The two-pointers approach is a method of iterating over an array with two variables, typically denoted as i and j. At every step during the iteration, we will search for the quadruplets similar to Triplet Sum to Zero whose sum is equal to the given Jan 26, 2025 · In this video, I talk about the two pointers technique which is a very important DSA topic for coding interviews. We then move the pointers based on the sum of the elements at these pointers. 2nd v Oct 15, 2019 · Description Discussion This tutorial delve into the powerful Two Pointer Approach. May 20, 2024 · This approach works by initializing two pointers, one at the beginning (left) and one at the end (right) of the array. Jan 7, 2024 · Recognizing Two Pointer Technique: The problem hints at the potential use of Two Pointers because it involves searching for a pair of elements that meet a specific condition (add up to the target). By using two pointers to traverse data structures (typically arrays or strings), we can The Two Pointer Technique The two pointer technique is a near necessity in any software developer's toolkit, especially when it comes to technical interviews. Aug 13, 2022 · The Time complexity of this solution is O (N) but the space complexity is only O (1), we use any extra space because of the two-pointers approach. Jul 23, 2025 · The Two Pointer Approach is a powerful and efficient technique used to solve problems involving sorted arrays, searching, and optimization. Otherwise, return NO. Learn how this technique can be used to solve a variety of algorithmic problems, especially those involving arrays or linked lists. 1st variant: Return YES if there exist two numbers such that their sum is equal to the target. In this guide, we'll cover the basics so that you know when and how to use this technique. It involves using two pointers or indices to solve problems by maintaining multiple positions in a sequence or array, often reducing time complexity and optimizing solutions for various coding challenges. Jul 12, 2025 · Two-Pointers approach: This problem follows the Two Pointers pattern and shares similarities with Triplet Sum to Zero. For this problem, the two-pointer helps us to reduce our space complexity we have a constant complexity instead of a linear. It helps solve problems that involve searching, sorting, or traversing arrays, strings, or linked lists in an efficient way. This is the best place to expand your knowledge and get prepared for your next interview. Now we add them and check if the sum value is equal to the key. LeetCode Problems solved in this video: Thanks for Watching! If you found this video helpful, check other Geekific Jul 1, 2022 · Different approaches to tackle the Two Sum problem with explanation and time and space complexity Two Sum - Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target. At its core, the idea is simple. As a self-taught developer (no theoretical CS background), learning data … Jul 23, 2025 · Using Recursion - O (n) time and O (n) space This approach is similar to our two pointers approach that we have discussed above. By using two pointers to traverse data structures (typically arrays or strings), we can Jul 23, 2025 · The Two Pointer Approach is a powerful and efficient technique used to solve problems involving sorted arrays, searching, and optimization. Aug 21, 2025 · Core The Two Pointers pattern is a common algorithmic technique used primarily to simplify problems that involve arrays or linked lists. This method is highly efficient when traversing arrays 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. The process of using a fast pointer and a slow pointer is another way to apply the two pointer technique, which can have O(n) time complexity and O(1) space complexity. What is the two pointer approach? As the name suggests, a two-pointer approach uses two-pointers to find the answer to a problem in the optimal time. . Base case: if the length of the string is 1 or less, it's considered a palindrome. util. Find the middle element of a linked list in Java using either the get () method or a single-pass two-pointer approach efficiently. In this optimized method, we use two pointers: one starting at the beginning of the list (left) and the other at the end (right). Watch replays of Two Pointer interviews. These pointers can move at different speeds or directions but are primarily used to compare, swap, or sum elements in a collection. Jul 11, 2023 · How Two Pointers work, when to use them in interviews, and common mistakes to avoid. These pointers can move towards each other, in the same direction, or even at different speeds. Jul 8, 2025 · The two-pointer technique is one of the most elegant and efficient algorithmic patterns in computer science. Apr 12, 2025 · The Two Pointer technique is one of the most intuitive yet powerful problem-solving strategies used in competitive programming and system design questions involving arrays, strings, and linked lists. See examples, code, and suggested problems for practice. It can be visualized as below: Now we got 2 elements from the 2 pointers. This type of two-pointer technique is particularly useful in scenarios where you want to find a pair of elements that meet certain conditions or when comparing elements from both ends. Nov 6, 2025 · Day 2: Reverse an array using two pointer approach This is a very commonly asked question. The text suggests that dividing complex problems into smaller subproblems can make them more manageable when using the two-pointer technique. Sep 3, 2020 · Let's learn about the Two Pointers technique to algorithm templates and two main variations of this technique. Mar 17, 2025 · The Two Pointers Technique is a straightforward but effective algorithmic technique that uses two pointers to traverse an array or linked list at the same time. Sep 9, 2025 · Basics of Two Pointer The two-pointer technique uses two indices that move towards each other or in the same direction to process data efficiently. Learn how it simplifies array and string problems with real-world examples and tips for coding interviews in 2025. Whenever an array question deals with finding two numbers in an array that satisfy a certain condition, either Jul 23, 2025 · Two pointers is really an easy and effective technique which is typically used for searching pairs in a sorted array. Problems on 2 Pointers are a test of your observation skills and how well you can deduce patterns. In the two pointer approach, one variable will be pointing at the starting index and another variable will be pointing at the ending index. We can follow a similar approach to iterate through the array, taking one number at a time. Jan 21, 2023 · One of these approaches goes by Two-Pointers and is the subject of this video. Learn how to use two pointers technique to iterate through a data set in a controlled way and solve problems that involve searching, comparing, or finding patterns. LeetCode Problems solved in this video: Thanks for Watching! If you found this video helpful, check other Geekific Jul 23, 2025 · Two pointers is really an easy and effective technique which is typically used for searching pairs in a sorted array. Aug 3, 2022 · Two pointer techniques — a visual tutorial Three animated two-pointer techniques to solve Three different problems. The idea to solve this problem is simple, we use two pointers import java. In this exclsuive video, we at Scaler, help you solve some Dec 22, 2024 · Now we shall try with 2 pointers approach. Using a two-pointer approach can expedite these calculations, thereby saving both computational resources and time. It is commonly used when: Data is sorted or the problem has sequential properties. Given a sorted array A (sorted in ascending order), having N integers, find if there exists any pair of elements (A [i], A [j]) such that their sum is equal to X. It … Aug 11, 2020 · Two-pointer technique is commonly used to solve array problems very efficiently. e. Mar 4, 2025 · Mastering the Two Pointer Approach: A Guide to Recognizing When to Use It Introduction The Two Pointer approach is one of the most efficient techniques in Data Structures and Algorithms (DSA). Common patterns in the two-pointer approach involve: Two pointers each starting from the beginning and the end until they both meet The two pointer approach is an efficient algorithmic technique used in computer science and programming. We need to find pairs/triplets or process subarrays without restarting from scratch. The more efficient an algorithm, the faster it can provide real-time insights, which is crucial in sectors like finance where time-sensitive decisions are the norm. Oct 15, 2019 · Description Discussion This tutorial delve into the powerful Two Pointer Approach. When the given data is present in a linear form i. Arrays; class Main { … Mar 28, 2024 · What is the Two Pointers Technique? The Two Pointers technique involves using two pointers to navigate through a data structure like an array or a string. The author believes that the two-pointer approach is often used for problems with a time complexity requirement, and it is essential to optimize for such. in terms of an array, vector, linked list, etc we can use this approach. Common patterns in the two-pointer approach involve: Two pointers each starting from the beginning and the end until they both meet One pointer moves at a slow pace while the other pointer moves at a faster pace Both of the above patterns can help Jul 23, 2025 · Whether it is searching, manipulation, optimization, or comparison, the two-pointer approach excels in various problem-solving scenarios. Two Pointers Technique Two pointers technique is a commonly used algorithmic approach to solve various problems that require linear time complexity. This technique is used to find a solution for problems that involve searching, sorting, or manipulating arrays, strings, or linked lists. Detailed solution for Two Sum : Check if a pair with given sum exists in Array - Problem Statement: Given an array of integers arr [] and an integer target. Jul 22, 2024 · Yes, by using a two-pointer approach. 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. This strategy involves the use Jul 22, 2024 · Yes, by using a two-pointer approach. It involves using two pointers, one pointing to the beginning of the data set and the other pointing to the end, and moving them towards each other based on specific conditions. The Two Pointers technique, as the name suggests, involves using two pointers to traverse an array or sequence. Dec 21, 2021 · There are more than 130/1300 problems in Leetcode that can be solved using two pointer approach. 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 Overview The two pointers technique is a technique used to iterate through a data set, typically an array or a list, in a controlled way. You may assume that each input would have exactly one solution, and you may not use the same element twice. Master the Two Pointers technique used in algorithmic problem-solving. Aug 21, 2025 · The two pointer technique is one of the most common and powerful patterns used in competitive programming, data structures, and algorithms. By using pointers, we can process two elements per loop, instead of just one. Jan 26, 2025 · In this video, I talk about the two pointers technique which is a very important DSA topic for coding interviews. Nov 18, 2022 · Aren't arrays amazing? They enable us to solve complex problems conveniently. Jul 23, 2025 · Whether it is searching, manipulation, optimization, or comparison, the two-pointer approach excels in various problem-solving scenarios. Here, we can use recursion to check the first and last letters of a string and then recursively check for remaining part of the string. Apr 1, 2024 · What is a Two-Pointer Algorithm? At its core, a two-pointer algorithm involves maintaining two pointers (indices or iterators) to traverse the dataset, typically an array or a string, to achieve a particular goal. Apr 4, 2025 · In the two-pointer approach, pointers refer to an array’s indexes.

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