Array of array products - dynamic programming algorithm - I got advice to declare variable leftToRight first, and then switch order of two statements of line 22 and line 24.

ArrayOfArrayProducts_DynamicProgramming.cs

using System;

class Solution
{
    public static int[] ArrayOfArrayProducts(int[] arr)
    {
     if(arr == null || arr.Length < 2)
       return new int[0]; 
      
     var length = arr.Length; 
     var product = new int[length]; 
      
     for(int i = 0; i < length; i++) 
     {
       product[i] = 1; 
     }
     
     var leftToRight = 1; 
     // left to right, one multiplication 
      for(int i = 0; i < length; i++)
      {        
        product[i]   = leftToRight; 
        
        leftToRight *= arr[i];
      }
      
      // right to left, two multiplication
      var rightToLeft = 1;       
      for(int i = length - 1; i >=0 ; i--)
      {
        product[i]  *= rightToLeft; 
        rightToLeft *= arr[i]; 
      }
      
      return product; 
    }

    static void Main(string[] args)
    {
    }
}

/*
dynamic programming 

iteration -> left to right 
product[] 
for iteration
  one multiplication

product[0] = 1
8, 10, 2
   *8  *10
  
second iteration from right to left

for each iteration 
 two mulitiplcations
 product[i] *= arr[i + 1] - two mulitiplcations
*/