523_Continuous_Subarray_Sum.py

"""
Given an integer array nums and an integer k, return true if nums has a continuous subarray of size at least two whose elements sum up to a multiple of k, or false otherwise.
An integer x is a multiple of k if there exists an integer n such that x = n * k. 0 is always a multiple of k.

Example 1:

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.

Example 2:
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.
"""

class Solution:
    def checkSubarraySum(self, nums: List[int], k: int) -> bool:
        hmap = { 0:-1 }
        totals = 0

        for i, n in enumerate(nums):
            totals += n
            rem = totals % k
            if rem not in hmap:
                hmap[rem] = i
            elif i - hmap[rem] > 1:
                return True
        else:
            return False