Range Sum

Problem Overview

• Count how many contiguous subarray sums fall within the inclusive range [lower, upper].
• Input: integer array nums and integers lower, upper; Output: an integer count of valid range sums.
• Range sums are sums of any continuous subarray; bounds are inclusive.
• Relevant to analytics on time-series or financial thresholds where sum ranges matter.
• Asked in Zolostays interviews; a common coding interview problem and interview question.