1590. Make Sum Divisible by P - Explanation

class Solution:
    def minSubarray(self, nums: List[int], p: int) -> int:
        n = len(nums)
        totSum = sum(nums)

        if totSum % p == 0:
            return 0

        for l in range(1, n):
            curSum = 0
            for i in range(n):
                curSum += nums[i]
                if i >= l:
                    curSum -= nums[i - l]

                remainSum = totSum - curSum
                if remainSum % p == 0:
                    return l

        return -1

class Solution:
    def minSubarray(self, nums: List[int], p: int) -> int:
        total = sum(nums)
        remain = total % p
        if remain == 0:
            return 0

        res = len(nums)
        cur_sum = 0
        remain_to_idx = {0: -1}

        for i, n in enumerate(nums):
            cur_sum = (cur_sum + n) % p
            prefix = (cur_sum - remain + p) % p
            if prefix in remain_to_idx:
                length = i - remain_to_idx[prefix]
                res = min(res, length)
            remain_to_idx[cur_sum] = i

        return -1 if res == len(nums) else res