using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(string.Join(",", ProductExceptSelf(new int[]{1,2,3,4})));

        Console.WriteLine(string.Join(",", ProductExceptSelf(new int[]{4, 5, 1, 8, 2, 10, 6})));

        Console.WriteLine(string.Join(",", ProductExceptSelf2(new int[]{1,2,3,4})));

        Console.WriteLine(string.Join(",", ProductExceptSelf2(new int[]{4, 5, 1, 8, 2, 10, 6})));

    }

    private static int[] ProductExceptSelf(int[] nums)

    {

        int len = nums.Length;

        int[] l2R = new int[len];

        l2R[0] = 1;

        for(int i = 1; i < len; i++)

        {

            l2R[i] = l2R[i - 1] * nums[i - 1];

        }

        int r = 1;

        for(int i = len - 1; i >= 0; i--)

        {

            l2R[i] = l2R[i] * r;

            r = r * nums[i];

        }

        return l2R;

    }

    private static int[] ProductExceptSelf2(int[] nums) {

        int len = nums.Length;

        int[] l2R = new int[len];

        int[] r2L = new int[len];

        l2R[0] = 1;

        for(int i = 1; i < len; i++)

        {

            l2R[i] = nums[i - 1] * l2R[i - 1];

        }

        r2L[len - 1] = 1;

        for(int i = len - 2; i >= 0; i--)

        {

            r2L[i] = nums[i + 1] * r2L[i + 1];

        }

        for(int i = 0; i < len; i++)

        {

            l2R[i] = l2R[i] * r2L[i];

        }

        return l2R;

    }

}