This is the second video in Series of Patterns we encounter during Leetcode Weekly and Biweekly Contests.
In this video, we cover Prefix Sum Technique - A Versatile Algorithm which helps in optimising queries. This technique can be used not just with sum but any operator which is invertible like Multiply, XOR, etc.
Problems to practice
Closest Cities: codeforces.com/contest/1922/p...
Number if subarrays with odd sum: leetcode.com/problems/number-...
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00:00-4:30 Range Query Sum Problem & Brute Force
4:31-5:22 Cumulative/Prefix Sum Concept
5:23-8:29 Using this concept for optimising range queries
8:30-11:46 Closest Cities Problem
11:47-12:26 Brute Force Solution
12:27-17:27 How Prefix sum can help optimise?