using System;

using System.Collections.Generic;

​

public class Program

{

    public static IList<int> FindDuplicates(int[] nums) {

        // ATTEMPT 2 - the proper way

        var lst = new List<int>();

​

        while (true)

        {

            int x = 0;

            int y = 0;

            bool duplicateDetected = false;

​

            do

            {

                x++;

                y += 2;

​

                if (x >= nums.Length)

                    x = x - nums.Length;

​

                if (y >= nums.Length)

                    y = y - nums.Length;

​

                Console.WriteLine($"{nums[x]} at {x} | {nums[y]} at {y}");

            }

            while (x != y);

​

            if (x == y)

            {

                // Reset one of the pointers to the beginning of the array

                x = 0;

​

                // Move both pointers at the same pace until they meet again

                while (x != y)

                {

                    x++;

                    y++;

                    if (y >= nums.Length)

                        y = y - nums.Length;

​

                    // Check for equality of elements

                    if (nums[x] == nums[y])

                    {

                        Console.WriteLine($"Duplicate element found: {nums[x]}");

                        duplicateDetected = true;

                        break;

                    }

                }

            }

​

            // If duplicate is detected or all elements have been checked, exit the while loop

            if (duplicateDetected || x == 0)

                break;

        }

​

        return lst;

    }

    public static void Main()

    {

        int[] nums = [4,3,2,7,8,2,3,1];

        var res = FindDuplicates(nums);

        foreach(var r in res)

            Console.WriteLine(r);

    }

}