Two Pointers Problems. Two Pointers | Three Sum Problem | C++ Placement Course | Lecture 26.

Two Pointers | Three Sum Problem | C++ Placement Course | Lecture 26. There are around 140 problems today, but I only solved the public ones (117 problems). io/Code solutions in Python, Java, C++ and JS for this can be found at my GitHub repo here: h The two pointer technique is a near necessity in any software developer's toolkit, especially when it comes to technical interviews. Classifications Same Directions These questions have two pointers that move in the same direction. Nov 7, 2025 · The Two Pointer technique is a pattern built on simple movement and precise logic. It covers a variety of questions, from basic to advanced. In simple words, this problem asks you to find the middle node of a linked list in one traversal. At least with graph problems, you just need to tweak dfs and bfs algos to figure them out. What You’ll Learn in This Video: What is the Two Sep 23, 2025 · Learning DSA Two Pointers Pattern using Java One of the most elegant tricks in problem-solving is the Two Pointers technique. It relies on two reference variables that travel through… Jan 10, 2026 · 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. Press the below buttons in the order in which they should occur. A list of problems (with animated solutions!) for you to try that build upon the concepts covered here. Established a set (2-3) of test cases to verify their own solution later. The types of problem for which you should consider using this technique. This is the two pointer solution: Jul 23, 2025 · The Two Pointer Approach is a powerful and efficient technique used to solve problems involving sorted arrays, searching, and optimization. As the name suggests, in this technique you have two pointers that are usually just variables pointing to the indices of the array. Learn how it simplifies array and string problems with real-world examples and tips for coding interviews in 2025. I remember the first time I learned it — it felt like magic Master the two-pointer method with interactive visuals and real-time coding exercises to solve array problems efficiently. From basic algorithms to advanced programming concepts, our problems cover a wide range of languages and difficulty levels. 5 months, and wanted to share my findings/classifications here. Interviewers like this problem because it checks your understanding of pointer movement, traversal logic, and optimization. Below is a list of practice problems from Leetcode that can be solved using the 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 Jul 8, 2025 · By using two pointers to traverse data structures (typically arrays or strings), we can solve complex problems with optimal time complexity, often transforming O (n²) solutions into O (n) Overall, the two pointers technique is a useful approach for solving specific types of problems that involve iterating through a data set in a controlled way, such as in pattern matching, data analysis, and statistics. 2 days ago · You’ll learn how to identify anomalies, how sorting changes the problem structure, where binary search and two pointers fit, and how to build robust code with modern testing and profiling habits. Introduction to Two Pointers Intuition As the name implies, a two-pointer pattern refers to an algorithm that utilizes two pointers. Click on them again to un-select. In this post, you will be going through 13 problems which kind of sets the tone for the other We would like to show you a description here but the site won’t allow us. length <= 1000 * s consist of only digits and English letters. This is the 1st Video on our Two Pointer Technique playlist. Perfect for students, developers, and anyone looking to enhance their coding knowledge and technical abilities. Master the Two Pointers and Sliding Window techniques with Abhinav Awasthi in this detailed tutorial! Whether you're preparing for coding interviews, competi Master the Two Pointers and Sliding Window techniques with Abhinav Awasthi in this detailed tutorial! Whether you're preparing for coding interviews, competi By using these operations, we are able to solve some basic problems. You may assume that each input would have exactly one solution, and you may not use the same element twice. In this exclsuive video, we at Scaler, help you solve some 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. In this guide, we'll cover the basics so that you know when and Feb 12, 2025 · Quiz on Two Pointer Technique for DSA Quiz will help you to test and validate your DSA knowledge. 5M subscribers Subscribed 📝 Must-Read Leetcode Articles Sliding Window Template Two Pointers Patterns Collections of Important String Questions Substring Problem Template Binary Search Template A General Approach to Backtracking Questions Monotonic Stack Template Heap Patterns Bit Manipulation Patterns Dynamic Programming Patterns Stock Series Patterns Apr 4, 2024 · The two-pointer technique is a widely used approach to solving problems efficiently, particularly scenarios involving arrays or linked lists. One usage is while searching for pairs in an array. io/Code solutions in Python, Java, C++ and JS for this can be found at my GitHub repo here: h Apr 3, 2024 · Master Data Structures & Algorithms for FREE at https://AlgoMap. We would like to show you a description here but the site won’t allow us. This method is highly efficient when traversing arrays Nov 17, 2023 · Practice and master all interview questions related to Two Pointers Dec 21, 2021 · There are more than 130/1300 problems in Leetcode that can be solved using two pointer approach. The two-pointer technique can also be used to solve problems that involve partition arrays into different regions. 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. Programming competitions and contests, programming community Level up your coding skills and quickly land a job. Aug 2, 2025 · The Two Pointers technique is one of the most efficient and elegant solutions for solving array and string problems that involve searching, partitioning, or comparison. A simple problem that illustrates the motivation behind the two-pointer technique. Jan 21, 2023 · One of these approaches goes by Two-Pointers and is the subject of this video. . g. Whether it is searching, manipulation, optimization, or comparison, the two-pointer approach excels in various problem-solving scenarios. Oct 19, 2020 · We have explained two pointer technique which is the optimal way to solve problems related to arrays in O (N) time. 1K Dislike 91 For string problems (like "at most K changes"), two pointers + frequency counters are your friends. Below are some classifications, although they are in no way exhaustive. Master Data Structures & Algorithms for FREE at https://AlgoMap. This method is highly efficient when traversing arrays 2: M-atch Match what this problem looks like to known categories of problems, e. You can acquaint yourself with how this approach is used. Explained why we should change our logic if input array is already sorted. pat The two-pointer technique can also be used to solve problems that involve partition arrays into different regions. Test your coding skills and improve your problem-solving abilities with our comprehensive collection of Two Pointers problems. Use this as a checklist or a guide to mastering this pattern. Explained what is two sum problem then what is the basic approach. Established a set (1-2) of edge Solve the most popular two pointers interview questions. The Two-Pointer Technique efficiently solves the "Two Sum Sorted" problem in a sorted array. Written by top USACO Finalists, these tutorials will guide you through your competitive programming journey. Iterating two monotonic pointers across an array to search for a pair of indices satisfying some condition in linear time. Conclusion The Two Pointers technique is a must-have weapon in a competitive programmer's arsenal. Sep 3, 2020 · Let's learn about the Two Pointers technique to algorithm templates and two main variations of this technique. It involves initializing two pointers, comparing their sum to the Nov 7, 2025 · The Two Pointer technique is a pattern built on simple movement and precise logic. In this blog post, I'll focus on one such technique: the two-pointer technique, which is particularly effective for tackling array or list problems. In this post, you will be going through 13 problems which kind of sets the tone for the other Jan 13, 2022 · Hello, I have been solving all two pointers tagged problems in last 3. Jan 26, 2025 · In this video, I talk about the two pointers technique which is a very important DSA topic for coding interviews. This is the best place to expand your knowledge and get prepared for your next interview. Example 2: Input: s = "cbbd" Output: "bb" Constraints: * 1 <= s. Idk if it's just me but i unironically feel like tree and graph problems are so much easier to figure out than substring and 2 pointer problems. Two pointers is a popular technique in the interview problems. Link for other im Level up your coding skills and quickly land a job. Both the next and random pointer of the new nodes should point to new nodes in the copied list such that the pointers in the original list and copied list represent the same list state. 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 The Two-Pointer Technique efficiently solves the "Two Sum Sorted" problem in a sorted array. 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). For these questions, each pointer represents where the next element belonging to that region should go. Jan 13, 2022 · Hello, I have been solving all two pointers tagged problems in last 3. If you are preparing for Level up your coding skills and quickly land a job. 1 Apna College 6. Stay tuned for more! Sep 7, 2025 · Here’s a list of important Two Pointers problems on LeetCode, curated with their strategies and direct links. Many algorithms just use a single pointer to attain or keep track of a single element: Usage: Two pointer approach can be used when you want to process two elements in a single iteration or determine a type of pattern. It relies on two reference variables that travel through… This technique shows how a nested for loop in some problems can be converted to a single for loop to reduce the time complexity. As an analogy, a page number in a book's index could be considered a pointer to the corresponding page; dereferencing such a pointer would be done by flipping to the page with the given page number and reading the text found on that page. It helps solve problems that involve searching, sorting, or traversing arrays, strings, or linked lists in an efficient way. Prepare for DSA interview rounds at the top companies. The best thing about this channel is, you will find the thought process behind every problem and not just simple algorithms. Patreon Link: https://www. Apr 4, 2024 · The two-pointer technique is a widely used approach to solving problems efficiently, particularly scenarios involving arrays or linked lists. Nov 2, 2025 · If you’ve been solving problems on LeetCode or preparing for technical interviews, you’ve likely come across the Two Pointer technique — one of the most elegant and efficient patterns in Sep 6, 2023 · Two Pointer Technique Two Pointer Technique is a useful strategy for solving a variety of array-based problems in a more efficient manner. If the sum of the two numbers pointed by the two pointers is smaller than the target sum, this means that we need a pair with a larger sum. All of the content is in English so that anyone can watch it. In this post, you will be going through 13 problems which kind of sets the tone for the other Sep 28, 2025 · By watching this, you'll learn how to approach array problems, find duplicates, and tackle pair sum or pair difference problems effectively. If you are preparing for Unit 10 Session 2 (Click for link to problem statements) Problem Highlights 💡 Difficulty: Medium ⏰ Time to complete: 20 mins 🛠️ Topics: Linked List, Two Pointers 1: U-nderstand Understand what the interviewer is asking for by using test cases and questions about the problem. For Populating Next Right Pointers, consider the following approaches: Level Order Traversal: Traverse the tree level by level, connecting nodes on the same level. Level up your coding skills and quickly land a job. In this chapter, we are going to talk about the two-pointer technique which can help us with many array/string related problems! But with thousands of problems on LeetCode, where do you even begin? Plus, it's easy to get stuck in random grinding. It does not matter what you leave beyond the returned k (hence they are underscores). Here is an example of a same direction two pointer question: Remove Duplicates. We will start with a brute force solution Level up your coding skills and quickly land a job. Let us consider a practical example: assume that you have a sorted array arr. In this exclsuive video, we at Scaler, help you solve some 2 days ago · Move Zeros is asked in almost every coding interview Tomorrow’s video shows the optimized two pointer solution Subscribe to CodeWithJalandhar for placements Dec 21, 2021 · There are more than 130/1300 problems in Leetcode that can be solved using two pointer approach. If you are preparing for technical interview, two pointers is one of the popular topics that you can't skip :). Order the following steps according to the general steps required for solving a problem using two-pointer technique. Two pointers. There are a lot of ways to classify two pointer problems. Example: Detecting loop in a linked list, checking palindrome in arrays, strings, and linked list, reversing a string or a linked list, two sum problem, finding the middle of a linked list, etc. 971K subscribers Subscribed 16K 722K views 1 year ago Two Pointer and Sliding Window Playlist | Language Independent Course Join Brilliant using the link bellow for 30-day free trial + 20% off the premium subscription https://brilliant. Sep 6, 2023 · Two Pointer Technique Two Pointer Technique is a useful strategy for solving a variety of array-based problems in a more efficient manner. In this video we will try to solve a very famous and interesting Problem "Reverse Vowels of a Str 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. Level up your coding skills and quickly land a job. Aug 21, 2025 · The two pointer technique is one of the most common and powerful patterns used in competitive programming, data structures, and algorithms. Two-Pointer Technique: Use two pointers to move across the Problems on 2 Pointers are a test of your observation skills and how well you can deduce patterns. It relies on two reference variables that travel through… In the other scenario, one pointer moves at a slow speed, while the other pointer moves at a fast speed, both of them moving in the same direction. Dec 21, 2021 · There are more than 130/1300 problems in Leetcode that can be solved using two pointer approach. You just have to assess all the given options and click on the correct answer. However, it is obviously not enough. Example 1: Input: s = "babad" Output: "bab" Explanation: "aba" is also a valid answer. Nov 11, 2022 · In this class, Urvi mam is teaching the concept of two pointers which is crucial if your goal is to learn to use arrays to their maximum capabilities. The actual format and content of a pointer variable is dependent on the underlying computer architecture. Instead, the real key is to master problem-solving Aug 10, 2024 · This is especially true given the wide variety of problems that can arise with arrays or lists. And oftentimes, that’s where most SDEs stumble. Essentially, it involves using two pointers (or indices) to traverse an array, often with each moving at a different speed or starting position. Two Pointer Technique Made Easy | Important Two Pointer Problems Solved Step by Step 2023 Data Structures Explained for Beginners - How I Wish I was Taught If the sum of the two numbers pointed by the two pointers is greater than the target sum, this means that we need a pair with a smaller sum. So, to try more pairs, we can decrement the end-pointer. Learn: Which digits remain valid after rotation How to check using two pointers Edge cases & clean intuition Perfect problem to develop the foundational mindset of the two-pointer technique. Dec 1, 2019 · Two Pointer Algorithm For Coding Interview: In this video, I have explained two pointer technique which is the optimal way to solve problems related to arrays, strings and linked list in O (N Nov 2, 2025 · If you’ve been solving problems on LeetCode or preparing for technical interviews, you’ve likely come across the Two Pointer technique — one of the most elegant and efficient patterns in Join over 28 million developers in solving code challenges on HackerRank, one of the best ways to prepare for programming interviews. I’ll use concrete examples, show complete implementations, and call out the common mistakes that make anomaly counters subtly wrong in production. Problems on 2 Pointers are a test of your observation skills and how well you can deduce patterns. Search "two pointers leetcode" @GregHogg Two Sum II - Leetcode 167 - 2 Pointers (Python) Two Sum II - Two Pointers Algorithm - Leetcode 167 6. , Linked List or Dynamic Programming, and strategies or patterns in those categories. LeetCode Problems solved in this video: Thanks for Watching! If you found this video helpful, check other Geekific Master the Two Pointers technique used in algorithmic problem-solving. Jan 10, 2026 · 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 quiz contains 13 questions. Jul 23, 2025 · The two-pointer approach is a valuable tool in the programmer, offering a versatile and efficient technique for solving array-related problems. Walk through of one of the most useful techniques, the two pointer, definitely worth knowing for coding interviews at companies like Microsoft, Amazon, Apple The provided content is a comprehensive guide detailing strategies and tips for solving two-pointer problems on LeetCode, including understanding indicators for such problems, employing various techniques, and solving classic examples. These pointers can move to, away, or in parallel with each other in a loop, depending on the problem and the invariant you are keeping. Codeforces. Most College Students Feel Lost When Starting DSA — Here’s a Smarter Way to Learn Jumping randomly between problems often leads to confusion. org/developedbyed/Leetcode challengeshttps: Example 1: Input: nums = [1,1,2] Output: 2, nums = [1,2,_] Explanation: Your function should return k = 2, with the first two elements of nums being 1 and 2 respectively. A free collection of curated, high-quality competitive programming resources to take you from USACO Bronze to USACO Platinum and beyond. 🔹 Can you solve this real interview question? Longest Palindromic Substring - Given a string s, return the longest palindromic substring in s.

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