Pairing Opposite Elements in Arrays with C#

Welcome! Today, I am excited to guide you through an intriguing task involving arrays: pairing up 'opposite' elements. Apart from arrays, we will dive deeper into learning about lists in C#. Lists offer more flexibility than arrays because they can dynamically resize and provide various useful methods for manipulating the collection of elements. This lesson will also include deeper explorations with tasks, providing an excellent opportunity to refine your array-handling and list-handling skills. Are you ready to start? Let's dive right in!

Before diving into the main lesson, let's briefly understand what a list is in C#. A list is a collection of objects that can be dynamically resized. Unlike arrays, lists are part of the System.Collections.Generic namespace and provide more flexibility:

• Dynamic Resizing: Lists can grow or shrink in size as needed.
• Additional Methods: Lists offer a rich set of methods such as Add, Remove, Insert, and more for easier manipulation of elements.

Here’s an example of how to declare and use a list in C#:

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List<int> numbers = new List<int> {1, 2, 3, 4, 5};
        
        // Add: Appends an element to the end of the list.
        numbers.Add(6); // The list now is {1, 2, 3, 4, 5, 6}

        // RemoveAt: Removes an element at a specified index. It accepts the index of the element to be removed.
        numbers.RemoveAt(0); // Removes element at index 0. The list now is {2, 3, 4, 5, 6}

        // Remove: Removes the first occurrence of a specific element.
        numbers.Remove(3); // Removes the element '3'. The list now is {2, 4, 5, 6}

        // Insert: Inserts an element at a specified index. Accepts the index and the element to be inserted.
        numbers.Insert(1, 9); // Inserts '9' at index 1. The list now is {2, 9, 4, 5, 6}
        
        foreach (int number in numbers)
        {
            Console.WriteLine(number);
        }
    }
}

Our task is to form pairs of 'opposite' elements in a given array of integers. In an array of n elements, we view the first and last elements as 'opposite,' the second and second last elements as 'opposite,' and so on. If the array length is odd, the middle element is its own 'opposite.'

You are provided with an array of n integers, with n ranging from 1 to 100, inclusive. The task necessitates that you return a list of arrays, where each array comprises a pair of an element and its 'opposite' element.

For example, for int[] numbers = {1, 2, 3, 4, 5, 6, 7}, the output should be Solution(numbers) = {{1, 7}, {2, 6}, {3, 5}, {4, 4}, {5, 3}, {6, 2}, {7, 1}}.