Question
Given a list of integers, find the smallest index i such that the sum of the elements strictly to the left of i equals the sum of the elements strictly to the right of i. The element at i itself belongs to neither side, and an empty side sums to 0. Return that index, or -1 if no such index exists. Values may be negative. Example: nums = [1, 7, 3, 6, 5, 6] gives 3, since 1 + 7 + 3 = 5 + 6 = 11.
pivot_index(nums: list[int]) → int[[1,7,3,6,5,6]]out3State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.
Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.