Count subarrays with target sum: Include negative values

What this Python exercise asks you to practise

This scenario tests count subarrays with target sum. It belongs to the Algorithm Foundations: Arrays, Searching, Sorting, and Hashing roadmap and uses the prefix sum · hash map · company screen pattern.

Complexity, linear and binary search, sorted() trade-offs, prefix ideas, two pointers, sliding windows, and hash-map patterns.

Pattern relevance

This exercise strengthens prefix sum · hash map · company screen. Be ready to explain the input, the rule, the boundary cases, and why the chosen approach is appropriate.