2D Prefix Sum | Tamil

🚀 Welcome back to the DSA in Tamil Series! In this session, we'll continue our journey with Difference Array by solving more practical Range Update problems and then move on to one of the most important 2D techniques in Data Structures — 2D Prefix Sum . If you've already learned the basics of Difference Array from the previous session, this video will help you strengthen that concept with more examples before extending the Prefix Sum idea from 1D arrays to 2D matrices . You'll learn how to preprocess a matrix so that any submatrix (rectangle) sum query can be answered in O(1) time. This technique is widely used in coding interviews, competitive programming, image processing, and grid-based problems. ━━━━━━━━━━━━━━━━━━━━ 📖 What you'll learn in this session Difference Array (Revision & Advanced) Quick recap of Difference Array Solving Range Update problems efficiently Applying multiple updates in O(1) per update Reconstructing the final array using Prefix Sum 2D Prefix Sum Why do we need 2D Prefix Sum? Building a 2D Prefix Sum matrix Understanding the Prefix Sum formula Answering Rectangle/Range Sum Queries in O(1) Avoiding double counting using the diagonal subtraction Time & Space Complexity ━━━━━━━━━━━━━━━━━━━━ ⏱️ Chapters 0:00:00 Intro 0:03:05 Maximum Sum Obtained of Any Permutation 0:22:20 Divide Intervals Into Minimum Number of Groups 0:46:56 Range Sum Query 2D - Immutable 1:12:51 Q&A ━━━━━━━━━━━━━━━━━━━━ 📺 DSA in Tamil Playlist    • LEARN DSA IN TAMIL      • Array Implementation Problem      • String Implementation Problems   Join the WhatsApp channel: https://whatsapp.com/channel/0029VbDF... ━━━━━━━━━━━━━━━━━━━━ 🌐 Connect with me 🔗 LinkedIn:   / rohinthr   🔗 LeetCode: https://leetcode.com/u/rohinth076/ 🔗 Twitter: https://x.com/rohinth_r ━━━━━━━━━━━━━━━━━━━━ If you find this session helpful, Like 👍, Share 📤, and Subscribe 🔔 to support the DSA in Tamil series. More interview-focused DSA topics and problem-solving sessions are coming soon! #DSA #PrefixSum #RangeSum #CodingInterview #CompetitiveProgramming #TamilProgramming #DSAInTamil #Algorithms #LeetCode #ProblemSolving 🎙️ New to streaming or looking to level up? Check out StreamYard and get ₹740 discount! 😍 https://streamyard.com/pal/d/59551969...