Count subarrays with sum equals k

Given an integer array `nums` (may contain negative numbers and zeros) and an integer `k`, return the **number of contiguous subarrays** whose sum is **exactly** `k`. ### Requirements - The subarray must be contiguous. - Your algorithm should handle negative values correctly. ### Input / Output - **Input:** `nums: int[]`, `k: int` - **Output:** `count: int` (number of contiguous subarrays with sum `k`) ### Example - `nums = [1, 2, 3], k = 3` → output `2` because subarrays `[1,2]` and `[3]` sum to 3.