Find Pivot Index

01 · Question

Given an array of integers nums, return the pivot index where the sum of the numbers to the left equals the sum of the numbers to the right.

02 · Solution

Reference solution

1def pivotIndex(nums: List[int]) -> int:
2    total = sum(nums)
3    left = 0
4    
5    for i, x in enumerate(nums):
6        if left == total - left - x:
7            return i
8        left += x
9    
10    return -1

Subarray Sum Equals K