Continuous Subarray Sum Python Solution

lcpy gen -n 523   # by problem number
lcpy gen -s continuous_subarray_sum   # by problem name

Input: nums = [23,2,4,6,7], k = 6
Output: true
Explanation: [2, 4] is a continuous subarray of size 2 whose elements sum up to 6.

Input: nums = [23,2,6,4,7], k = 6
Output: true
Explanation: [23, 2, 6, 4, 7] is an continuous subarray of size 5 whose elements sum up to 42.
42 is a multiple of 6 because 42 = 7 * 6 and 7 is an integer.

Input: nums = [23,2,6,4,7], k = 13
Output: false

class Solution:
    # Time: O(n)
    # Space: O(min(n, k))
    def check_subarray_sum(self, nums: list[int], k: int) -> bool:
        remainder_index: dict[int, int] = {0: -1}
        prefix = 0
        for i, num in enumerate(nums):
            prefix = (prefix + num) % k
            if prefix in remainder_index:
                if i - remainder_index[prefix] >= 2:
                    return True
            else:
                remainder_index[prefix] = i
        return False