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Data Structures for Coding Interviews in C#

Solution Review: Array of Products of All Elements

Explore how to solve the problem of computing the product of all elements in an array except the current index using efficient C# code. Understand a two-pass algorithm that calculates left and right products separately to achieve an O(n) time solution. Gain skills to implement this approach and improve your problem-solving techniques for coding interviews.

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Solution #

C#
namespace chapter_2
{
    class Solution
    {
        // Array of Products of all Elements
        static int[] findProduct(int []arr, int size)
        {
            int n = size;
            int i, temp = 1;
            int[] product = new int[n];  // Allocate memory for the product array
                                        // temp contains product of elements on left side excluding arr[i]
            for (i = 0; i < n; i++)
            {
                product[i] = temp;
                temp *= arr[i];
            }
            temp = 1;  // Initialize temp to 1 for product on right side
            // temp contains product of elements on right side excluding arr[i]
            for (i = n - 1; i >= 0; i--)
            {
                product[i] *= temp;
                temp *= arr[i];
            }
            return product;
        }
        static void Main(string[] args)
        {
            int size = 4;
            int []arr = { 1, 3, 4, 5 };
            Console.Write( "Array before product: ");
            for (int i = 0; i < size; i++)
            {
                Console.Write(arr[i] + " ");
            }
            Console.WriteLine("");
            int[] prodArray = findProduct(arr, size);
            Console.Write("Array after product: ");
            for (int i = 0; i < size; i++)
            {
                Console.Write(prodArray[i] + " ");
            }
           
            return ;
        }
    }
}

Explanation

In this problem, you need to calculate the product of elements in a specific way. In the output array, the value at index i will be equal to the product of all the elements of the given array arr ...