Data Structures19 sections · 729 units
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Problem - Count of Range Sum

Coordinate compression

Given an integer array nums and two integers lower and upper, return the number of range sums that lie in [lower,upper][\text{lower}, \text{upper}] inclusive.

Range sum S(i,j)S(i, j) is the sum of elements from index ii to jj where iji \leq j. Example: nums =[2,5,1]= [-2, 5, -1], lower =2= -2, upper =2= 2. Range sums: 2,3,2,5,4,1-2, 3, 2, 5, 4, -1.

In range: 2,2,1-2, 2, -1. Answer: 33. This you can solve with segment tree + coordinate compression on prefix sums. Constraints: up to 10510^5 elements, values up to 10910^9.