using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using ExtensionMethods;

​

namespace ExtensionMethods

{

    public static class MyExtensions

    {

        public static bool ContainsAll(this IEnumerable<int> items, IEnumerable<int> itemsToFind)

        {

            return itemsToFind.All(currentItem => items.Contains(currentItem));

        }

​

        public static bool HashSetContainsAll(this IEnumerable<int> items, IEnumerable<int> itemsToFind)

        {

            HashSet<int> hashSet = new HashSet<int>();

​

            foreach (var item in items) hashSet.Add(item); //O(1)*m

​

            foreach (var item in itemsToFind) if (!hashSet.Contains(item)) return false; //O(1)*n

​

            return true;

        }

​

    }

}

​

    class EnumerableSetofInt : IEnumerable<int>

    {

        private int[] integers;

​

        public EnumerableSetofInt(int size)

        {

            integers = new int[size];

​

            Random random = new Random();

​

            for (int i = 1; i <= size; i++)

            {

                int nextPos;

​

                for (

                    nextPos = random.Next(0, size-1); 

                    integers[nextPos] > 0; 

                    nextPos = (nextPos < integers.Length-1) ? nextPos + 1 : 0

                    );

​

​

                integers[nextPos] = i;

            }

​

        }

​

        public IEnumerator<int> GetEnumerator()

        {

            return ((IEnumerable<int>)integers).GetEnumerator();

        }

​

        IEnumerator IEnumerable.GetEnumerator()

        {

            return ((IEnumerable<int>)integers).GetEnumerator();

        }

    }

    public class Program

    {

        public static long CurrentTimeMillis()

        {

            return (long)(DateTime.UtcNow - (new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc))).TotalMilliseconds;

        }

        public static void Main()

        {

            EnumerableSetofInt numbers = new EnumerableSetofInt(200000);

​

            EnumerableSetofInt toFind = new EnumerableSetofInt(100000);

​

            /*foreach (var nextInt in numbers)

            {

                Console.Write($"->{nextInt}");

            }

​

            Console.WriteLine();

​

            foreach (var nextInt in toFind)

            {

                Console.Write($"->{nextInt}");

            }*/

​

            Console.WriteLine();

​

            long currentTimeMillis = CurrentTimeMillis();

​

            Console.WriteLine(numbers.ContainsAll(toFind) ? "Found them All" : "Not all were found");

​

            Console.WriteLine("ContainsAll Took: " + (CurrentTimeMillis() - currentTimeMillis) + " milliseconds");

​

            currentTimeMillis = CurrentTimeMillis();

​

            Console.WriteLine(numbers.ContainsAll(toFind) ? "Found them All" : "Not all were found");

​

            Console.WriteLine("GersonContainsAll Took:" + (CurrentTimeMillis() - currentTimeMillis) + " milliseconds");

​

            Console.ReadLine();

        }

    }