The code was written very well, but first writing failed test case with array with size 1, the result should be empty array instead of 1.

arrayOfProduct_practice.cs

using System;

class Solution
{
    public static int[] ArrayOfArrayProducts(int[] arr) // [8, 10, 2]
    {
      if(arr == null || arr.Length <= 1) // false
      {
        return new int[0]; 
      }
      
      int length = arr.Length; // 3
      var product = new int[length]; // 3
      
      var previousProduct = 1;      // 1 
      // first iteration from left to right 
      for(int i = 0; i < length; i++)  // [8,10,2] -> [1,8, 80]
      {        
        product[i] = previousProduct; 
        previousProduct *= arr[i]; // 8, 8 * 10
      }
      
      // second iteration from right to left
      previousProduct = 1; 
      for(int i = length - 1; i >= 0 ; i --) // [8, 10, 2]
      {
        product[i] *= previousProduct; 
        previousProduct *= arr[i]; // 2, 10 * 2
      }
      
      return product; 
    }

    static void Main(string[] args)
    {
      var product = ArrayOfArrayProducts(new int[]{8, 10, 2}); 
      foreach(var item in product)
      {
        Console.WriteLine(item); 
      }
    }
}

//[8, 10, 2] 
// right side 10 * 2, space complexity O()
//brute force n - 1, n -> O(n * n - 1) -> lower O(n)
// product[n]
// left -> right 1, 8, 8 * 10, 
// second, right -> left 
// [10 * product[i+1],2,1] -> O(n)
// [1, 8, 20] -> left to right 
// variable -> leftNeighborProduct 1, 2, 20
// [20, 2, 1] -> right to left 
// n -> 1 * 20, 8 * 2, 20 * 1,  space O(n), time complexity O(n)