using System;

public class Program

{

    public static void Main()

    {

        //int[] numbers = {10, 20, 30}; // new int[3];

        //numbers[0] = 10;

        //numbers[1] = 20;

        //numbers[2] = 30;

        //Console.WriteLine(numbers.Length);

        //Console.WriteLine(string.Join(" ", numbers));

        var array = new Array(3);

        array.Insert(10);

        array.Insert(20);

        array.Insert(30);

        array.Reverse();

        Console.WriteLine("");

        array.Print();

        Console.WriteLine("");

        array.InsertAt(45, 1);

        array.Insert(40);

        array.Insert(35);

        array.Reverse();

        Console.WriteLine("");

        array.RemoveAt(3);

        Console.WriteLine(array.IndexOf(10));

        Console.WriteLine("biggest number: " + array.Max());

        array.Print();

        var compareArray = new int[4] { 10, 15, 30, 95 };

        array.Intersect(compareArray);

    }

}

​

public class Array 

{

    int[] _numbers = null;

    int _count;

    public Array(int maxLength)

    {

        _numbers = new int[maxLength];

    }

    public void Insert(int node)

    {

        if (_numbers.Length <= _count)

          CopyArray();

        _numbers[_count] = node;

        _count++;

    }

    private void CopyArray()

    {

        var numbers = new int[_count * 2];

        for (var i = 0; i < _count; i++ )

            numbers[i] = _numbers[i];

        _numbers = numbers;

    }

    public void RemoveAt(int index)

    {

        if (index < 0 || index >= _count)

            throw new IndexOutOfRangeException();

        for (var i = index;  i < _count; i++)

            _numbers[i] = _numbers[i + 1];

        _count--;

    }

    public int IndexOf(int value)

    {

        for (var i = 0; i < _count; i++)

            if (_numbers[i] == value)

                return i;

        return -1;

    }

    public int Max()

    {

        var biggestNumber = 0;

        for (var i = 0; i < _count; i++)

            if (_numbers[i] > biggestNumber)

                biggestNumber = _numbers[i];

        return biggestNumber;

    }

    public void Intersect(int[] compareList)

    {

        if (compareList == null)

            throw new ArgumentNullException();

        var intersectList = new int[compareList.Length];

        var currentCount = 0;

        for (var i = 0; i < compareList.Length; i++)

        {

            for (var j = 0; j < _count; j++)

                if (compareList[i] == _numbers[j])

                {

                    intersectList[currentCount] = compareList[i];

                    currentCount++;

                }

        }

        for (var i = 0; i < currentCount; i++)

            Console.WriteLine(intersectList[i]);

    }

    public void Reverse()

    {

        var reverseList = new int[_count];

        for (var i = 0; i < _count; i++)

            reverseList[i] = _numbers[_count - i - 1];

                Console.WriteLine(string.Join(",",reverseList));

    }

    public void InsertAt(int item, int index)

    {

        if (index < 0 || index > _count + 1)

            throw new IndexOutOfRangeException();

        var originalArray = _numbers;

        if (_numbers.Length <= _count + 1)

          CopyArray();

        for (var i = index + 1; i < _count + 1; i++)

            _numbers[i] = originalArray[i - 1];

​

        _numbers[index] = item;

        Console.WriteLine(string.Join(",", _numbers));

    }

    public void Print()

    {

        for (var i = 0; i < _count; i++)

            Console.WriteLine(_numbers[i]);

    }

}

​