1588. Sum of All Odd Length Subarrays

Problem

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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.

Example 1:

Input: arr = [1,4,2,5,3]
Output: 58
Explanation: The odd-length subarrays of arr and their sums are:
[1] = 1
[4] = 4
[2] = 2
[5] = 5
[3] = 3
[1,4,2] = 7
[4,2,5] = 11
[2,5,3] = 10
[1,4,2,5,3] = 15
If we add all these together we get 1 + 4 + 2 + 5 + 3 + 7 + 11 + 10 + 15 = 58

Example 2:

Input: arr = [1,2]
Output: 3
Explanation: There are only 2 subarrays of odd length, [1] and [2]. Their sum is 3.

Example 3:

Input: arr = [10,11,12]
Output: 66

Constraints:

• 1 <= arr.length <= 100
• 1 <= arr[i] <= 1000

Solution

/**
 * @param {number[]} arr
 * @return {number}
 */
var sumOddLengthSubarrays = function(arr) {
  let nums = 1,
  tmp = [];

  while (nums <= arr.length) {
  for(let i = 0; i < arr.length + 1 - nums; i++) {
    tmp.push.apply(tmp, arr.slice(i, i + nums))
  }
  nums += 2;
}
  return tmp.reduce((acc, cur) => acc + cur, 0);
};