Divisible Sum Pairs Solution | HackerRank DSA Problem Explained | #Beginner in #DSA

In this video, I walk you through the solution to the HackerRank problem "Divisible Sum Pairs", where the task is to count the number of pairs (i, j) such that the sum of arr[i] + arr[j] is divisible by a given integer k. The challenge is to solve this problem efficiently. Problem Overview: You are given an array arr of integers and an integer k. You need to find how many pairs (i, j) (with i less than j) exist such that the sum of arr[i] + arr[j] is divisible by k. Approach: Brute Force Method: We could start by checking all pairs and counting the ones that satisfy the condition. However, this method may be too slow for larger inputs. Optimized Approach (Using Modulo Arithmetic): A more efficient approach involves using remainders when dividing by k. We can use a frequency array to keep track of remainders and then use that to find valid pairs in linear time. In this video, you'll learn: How to solve the problem step-by-step. Efficient code that reduces time complexity from O(n²) to O(n). Detailed explanation of the modulo arithmetic used to solve the problem. Watch the full video to see a detailed breakdown and example of the code in action! If you found this video helpful, don't forget to like, comment, and subscribe for more coding tutorials and problem-solving strategies! #HackerRank #DivisibleSumPairs #Coding #Programming #Python #Algorithm #ProblemSolving #CodeExplanation #InterviewPreparation #CompetitiveProgramming