Find All Subarrays With a Given Sum

Problem Given an integer array (which may contain negative numbers) and a target value, count the number of contiguous subarrays whose elements sum to the target.

Input / Output

• Input: integer array nums and integer target.
• Output: the count of contiguous subarrays summing to target.

Constraints

• 1 ≤ n ≤ 10^4.
• Values may be negative, so a sliding window does not apply.
• Subarrays are contiguous; the empty subarray is not counted.

Example

• [1,2,3], target = 3 → 2 ([1,2] and [3]).
• [1,-1,0], target = 0 → 3 — the negatives are exactly why a sliding window fails here.