Longest subarray sum equals target

Given a list of integers (positive, zero, or negative) and a target k, return the length of the longest contiguous run of elements whose sum is exactly k. Return 0 if no such run exists. Runs must be non-empty. Example: nums = [1, -1, 5, -2, 3], k = 3 gives 4, because 1 + (-1) + 5 + (-2) = 3 is the longest qualifying run.