Given an integer array nums and an integer k, return true if there's a subarray of length at least 2 whose sum is a multiple of k.
With nums = [23, 2, 4, 6, 7] and k = 6, the answer is true. The subarray [2, 4] sums to 6, which is a multiple of 6.
This combines prefix sums with modular arithmetic. How can remainders help you find subarrays divisible by k?
Constraints: , values from to , .