在C#中跨多个列表查找公共项的最快方法

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List<int> list1 = new List<int> { 1, 2, 3, 4, 5 };
        List<int> list2 = new List<int> { 4, 5, 6, 7, 8 };
        List<int> list3 = new List<int> { 7, 8, 9, 10, 11 };

        HashSet<int> hashSet1 = new HashSet<int>(list1);
        HashSet<int> hashSet2 = new HashSet<int>(list2);
        HashSet<int> hashSet3 = new HashSet<int>(list3);

        hashSet1.IntersectWith(hashSet2);
        hashSet1.IntersectWith(hashSet3);

        Console.WriteLine("公共项为：");
        foreach (int item in hashSet1)
        {
            Console.WriteLine(item);
        }
    }
}