Subarray Sum Equals K | Dataford Interview Questions

Subarray Sum Equals K (LeetCode 560): count contiguous subarrays whose sum equals k; must handle zeros and negative values.

Asked in the Round 1, 45-minute coding stage. The interviewer hinted to use a hash map, with a follow-up to optimize beyond storing all subarray sums.

Contract

Implement subarray_sum(nums, k). nums is a list of integers and k is an integer. Return the integer count of contiguous, non-empty subarrays whose elements sum to k.

Constraints

1 <= len(nums) <= 10000
-1000 <= nums[i] <= 1000
-10000000 <= k <= 10000000
Return the count of non-empty contiguous subarrays.

Function Signature

def subarray_sum(nums, k):

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