Find Pivot Index

Easy

Given an array nums, return the leftmost pivot index: the index where the sum of all numbers strictly to the left equals the sum strictly to the right. Return -1 if none exists.

Example 1

Input:  nums = [1,7,3,6,5,6]
Output: 3

Example 2

Input:  nums = [1,2,3]
Output: -1

Example 3

Input:  nums = [2,1,-1]
Output: 0

Constraints

• 1 <= nums.length <= 10^4
• -1000 <= nums[i] <= 1000