Subarray Sum Equals K

Function Name: subarraySum

Description

Write a function subarraySum that takes an array of integers and an integer value k as its parameters.

The function should return the number of continuous subarrays whose sum equals to k.

A subarray is a contiguous part of the array.

Requirements

• The function should take two parameters: an array of integers (nums) and an integer (k).
• The function should return an integer representing the number of subarrays that sum up to k.
• The array may contain positive, negative, or zero values.
• The function should be able to handle an empty array, in which case the return value should be 0 if k is not 0.
• Time complexity should be efficient and should avoid the brute force solution that checks every possible subarray sum.

Examples

Example 1: subarraySum([1, 1, 1], 2) should return 2.Example 2: subarraySum([-1, -1, 1], 0) should return 1.Example 3: subarraySum([10, 2, -2, -20, 10], -10) should return 3.

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