C# program to find common elements in three arrays using sets

int[] arr1 = {
   99,
   57,
   63,
   98
};

int[] arr2 = {
   43,
   99,
   33,
   57
};

int[] arr3 = {
   99,
   57,
   42
};

// HashSet One
var h1 = new HashSet < int > (arr1);
// HashSet Two
var h2 = new HashSet < int > (arr2);
// HashSet Three
var h3 = new HashSet < int > (arr3);

using System;
using System.Collections.Generic;
using System.Linq;

public class Program {
   public static void Main() {
      int[] arr1 = {
         99,
         57,
         63,
         98
      };

      int[] arr2 = {
         43,
         99,
         33,
         57
      };

      int[] arr3 = {
         99,
         57,
         42
      };

      // HashSet One
      var h1 = new HashSet < int > (arr1);
      // HashSet Two
      var h2 = new HashSet < int > (arr2);
      // HashSet Three
      var h3 = new HashSet < int > (arr3);

      // Displaying
      int[] val1 = h1.ToArray();
      Console.WriteLine("Set one...");
      foreach(int val in val1) {
         Console.WriteLine(val);
      }

      //Displaying
      int[] val2 = h2.ToArray();
      Console.WriteLine("Set two...");
      foreach(int val in val2) {
         Console.WriteLine(val);
      }

      //Displaying
      int[] val3 = h3.ToArray();
      Console.WriteLine("Set three...");
      foreach(int val in val3) {
         Console.WriteLine(val);
      }

      int i = 0, j = 0, k = 0;
      Console.WriteLine("Common elements...");
      while (i < val1.Length && j < val2.Length && k < val3.Length) {
         if (val1[i] == val2[j] && val2[j] == val3[k]) {
            Console.Write(val1[i] + " ");
            i++;
            j++;
            k++;
         }
         // x < y
         else if (val1[i] < val2[j])
         i++;
         // y < z
         else if (val2[j] < val3[k])
         j++;
         else
         k++;
      }
   }
}