Prefix Sums · Range Queries in O(1)
unseel.com · cumulative sum · P[r+1] − P[l] · O(1) query
n 8
query [l,r]
answer
phase
value bar a[i]
prefix cell P[i]
query range [l, r]
answer P[r+1] − P[l]
Unseel.com · Prefix Sums