https://leetcode.com/problems/find-pivot-index/description/?envType=study-plan-v2&envId=leetcode-75

class Solution:
def pivotIndex(self, nums: List[int]) -> int:
total = sum(nums)
nums = [0] + nums
for i in range(1, len(nums)):
nums[i] += nums[i-1]
for i in range(1, len(nums)):
if (nums[i] + nums[i-1]) == total:
return i - 1
return -1