Find Pivot Index – My solution for leetcode problem

Problem

Given an array of integers nums, calculate the pivot index of this array.

The pivot index is the index where the sum of all the numbers strictly to the left of the index is equal to the sum of all the numbers strictly to the index’s right.

If the index is on the left edge of the array, then the left sum is 0 because there are no elements to the left. This also applies to the right edge of the array.

Return the leftmost pivot index. If no such index exists, return -1.

Example 1:

Input: nums = [1,7,3,6,5,6]
Output: 3
Explanation:
The pivot index is 3.
Left sum = nums[0] + nums[1] + nums[2] = 1 + 7 + 3 = 11
Right sum = nums[4] + nums[5] = 5 + 6 = 11

Example 2:

Input: nums = [1,2,3]
Output: -1
Explanation:
There is no index that satisfies the conditions in the problem statement.

Example 3:

Input: nums = [2,1,-1]
Output: 0
Explanation:
The pivot index is 0.
Left sum = 0 (no elements to the left of index 0)
Right sum = nums[1] + nums[2] = 1 + -1 = 0

Constraints:

• 1 <= nums.length <= 104
• -1000 <= nums[i] <= 1000

Solution:

/**
 * @param {number[]} nums
 * @return {number}
 */
var pivotIndex = function(nums) {
    const total = nums.reduce((a, b) => a + b, 0);

  let leftSum = 0
  
  for (i=0; i<nums.length; i++) {
		    
  
     let rightSum = total - leftSum - nums[i]
           
     if (leftSum === rightSum) {
   	return i
     }
     
     leftSum += nums[i]
  
  }
  
  return -1
};

• It first calculates the total sum of all the elements in the input array nums using the reduce() method and stores it in the variable total.
• It initializes variable leftSum.
• It then loops through each element of the nums array using a for a loop.
• Inside the loop, it calculates the sum of the elements to the right of the current element by subtracting the leftSum and the current element’s value from the total.
• It checks if the leftSum and rightSum are equal. If they are, it means that the current element is the pivot. In this case, the function returns the index of the current element.
• If the leftSum and rightSum are not equal, it adds the current element’s value to the leftSum variable.
• After the loop completes, if no pivot is found, the function returns -1.