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Coding/Arrays and strings

Find balance index

Write codeMedium15 min

Your task

Given a list of integers, find the leftmost balance index: a position where the sum of all entries strictly to its left equals the sum of all entries strictly to its right (the entry at the position itself joins neither side). Sums over no entries count as 0. Return that index, or -1 if no position balances. Example: [1, 7, 3, 6, 5, 6] returns 3, since 1+7+3 = 5+6.

Examples

balance_index(nums: list[int]) -> int
Example 1
Inputbalance_index([1, 7, 3, 6, 5, 6])
Output3