2256. Minimum Average Difference

class Solution:
    def minimumAverageDifference(self, nums: List[int]) -> int:
        pre, suf = 0, sum(nums)
        n = len(nums)
        res, mi = 0, inf
        for i, x in enumerate(nums):
            pre += x
            suf -= x
            a = pre // (i + 1)
            b = 0 if n - i - 1 == 0 else suf // (n - i - 1)
            if (t := abs(a - b)) < mi:
                res = i
                mi = t
        return res