class Solution724:
    def pivotIndex(self, nums: List[int]) -> int:
        res = -1
        n = len(nums)
        if n == 0:
            return -1
        elif n == 1:
            return 0
        elif n < 3:
            return -1
        else:
            sum_list = [0 for i in range(n)]
            sum_list[0] = nums[0]
            for j in range(1, n):
                sum_list[j] = sum_list[j - 1] + nums[j]
            if sum_list[n - 1] == sum_list[0]:
                return 0
            for j in range(1, n - 1):
                if sum_list[j - 1] == sum_list[n - 1] - sum_list[j]:
                    return j
            if sum_list[n - 2] == 0:
                return n - 1
        return res