Range update in constant time(per query)

use this when the no of queries for actual array elemnts after update is less than number of update qurries. prefix sum video link: https://youtu.be/EjtGjvYKAnM problem links: kj and street lights: https://www.hackerrank.com/contests/ab-yeh-kar-ke-dikhao/challenges/kj-and-street-lights street Lights: https://www.hackerrank.com/contests/algoholic-contest-1/challenges/street-lights/problem Prateek and theories: https://www.hackerearth.com/practice/algorithms/dynamic-programming/introduction-to-dynamic-programming-1/practice-problems/algorithm/prateek-and-theories-3/ B. Karen and Coffee: https://codeforces.com/contest/816/problem/B