class Solution:
    def maxSubArrayLen(self, nums, k):
        
        sum_lookup = {}
        acc_sum = 0 # accumulated sum
        length = 0 
        
        for index, num in enumerate(nums):
            acc_sum += num 
            sum_lookup[acc_sum] = index
        
            # if the sub array starts from the first location in nums array we use the length up to that point
            # example [1, -1, 0, 2, 3], K = 2 answer is 4 
            if acc_sum == k:
                length = index + 1
            
            # search "O(1) using hashmap" for any accumulated sum that is = acc_sum - k then measure the difference of indexes length
            # example [3, 4, 7, 2, -3, 1, 4, 2], k = 7 answer is 4
            elif acc_sum - k in sum_lookup:
                length = max(length, index - sum_lookup[acc_sum - k])

        return length