#2574 - Left and Right Sum Differences

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Problem Description

You are given a 0-indexed integer array nums of size n.

Define two arrays leftSum and rightSum where:

leftSum[i] is the sum of elements to the left of the index i in the array nums. If there is no such element, leftSum[i] = 0.
rightSum[i] is the sum of elements to the right of the index i in the array nums. If there is no such element, rightSum[i] = 0.

Return an integer array answer of size n where answer[i] = |leftSum[i] - rightSum[i]|.

Solution

/**
 * @param {number[]} nums
 * @return {number[]}
 */
var leftRightDifference = function(nums) {
  const n = nums.length;
  const result = new Array(n).fill(0);
  let leftSum = 0;
  let rightSum = nums.reduce((sum, num) => sum + num, 0);

  for (let i = 0; i < n; i++) {
    rightSum -= nums[i];
    result[i] = Math.abs(leftSum - rightSum);
    leftSum += nums[i];
  }

  return result;
};