sum of two array elements, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
                // Two Sum : sum of two array elements should be equal to the given target
            int[] nums = new int[] { 1, 4, 45, 6, 10, 8 }; 
            int target = 16; 
            
            Console.WriteLine("Target number is : " + target );
            Console.WriteLine("Input array is : " );
            Display(nums);
            int [] B = TwoSum(nums, target);
            
            Console.WriteLine("Result array is : " );
            Display(B);
        }
        
        public static int[] TwoSum(int[] nums, int target) {
            int [] arr = new int[1];
            HashSet<int> hs = new HashSet<int>(); 
            for (int indx = 0; indx < nums.Length; ++indx) { 
                int num1 = target - nums[indx]; 
                if (hs.Contains(num1)) { 
                    arr = new int[] {num1, nums[indx]} ;
                } 
                hs.Add(nums[indx]); 
            } 
           return arr;
        }
        
           // Display the array 
        static void Display(int []arr) 
        { 
            int size = arr.Length; 
            for (int indx=0; indx < size; ++indx) 
                Console.Write(arr[indx] + " "); 
            Console.WriteLine(); 
        }
        
        
    }
    
    
}

Show compiler warnings [ + ] Show input
Compilation time: 0,36 sec, absolute running time: 0,27 sec, cpu time: 0,27 sec, average memory usage: 18 Mb, average nr of threads: 3, absolute service time: 0,69 sec