#1588 - Sum of All Odd Length Subarrays

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Problem Description

Given an array of positive integers arr, return the sum of all possible odd-length subarrays of arr.

A subarray is a contiguous subsequence of the array.

Solution

/**
 * @param {number[]} arr
 * @return {number}
 */
var sumOddLengthSubarrays = function(arr) {
  let result = 0;

  for (let index = 0; index < arr.length; index++) {
    result += arr[index] * Math.ceil(((index + 1) * (arr.length - index)) / 2);
  }

  return result;
};