using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

​

namespace Massive

{ 

    public class Methods

    {

        public static void ShowArray(int[] a)

        {

            foreach (int number in a)

                Console.Write(number + ";" + " ");

            Console.WriteLine();

        }

        public static void ShowResult(int a)

        {

            Console.WriteLine(a);

        }

        public static int GetNegativeElements(int[] a)

        {

            int countNegative = 0;

            for (int i = 0; i < a.Length; i++)

            {

                if (a[i] < 0) countNegative = countNegative + 1;

            }

            return countNegative;

        }

        public static int GetMinValue(int[] a)

        {

            int minValue = a[0];

            for (int i = 1; i < a.Length; i++)

            {

                if (a[i] < minValue) minValue = a[i];

            }

            return minValue;

        }

        public static int GetMaxValue(int[] a)

        {

            int maxValue = a[0];

            for (int i = 0; i < a.Length; i++)

            {

                if (a[i] > maxValue) maxValue = a[i];

            }

            return maxValue;

        }

        public static int GetElementsQuantity(int[] a)

        {

            int countI = 0;

            for (int i = 0; i < a.Length; i++)

            {

                countI = countI + 1;

            }

            return countI;

        }

        public static void ReverseArray(int[] a)

        {

            int j = a.Length - 1;

            for (int i = 0; i < a.Length / 2; i++, j--)

            {

                {

                    int temp = a[i];

                    a[i] = a[j];

                    a[j] = temp;

                }

            }

        }

       /* public static int[] PozitiveArray(int[] a)

        {

            int[] pozitive = new int[a.Length - Methods.GetNegativeElements(a)];

            for (int i = 0, j = 0; i < a.Length; i++)

            {

                if (a[i] >= 0)

                {

                    pozitive[j] = a[i];

                    j++;

                }

            }

            return pozitive;

        }*/

​

        public static int CountElementsSum(int[] a)

        {

            int sum = 0;

            for (int i = 0; i < a.Length; i++)

            {

                sum = sum + a[i];

            }

            return sum;

        }

        public static bool IsEven (int a)

         {

            return a % 2 == 0;     //то же, что и if (a % 2== 0) return true;

        }

        public static int [] Filter (int[] array, int filteredLength, Func <int, bool> checkElement)

        {

            int[] newMas = new int[filteredLength];

            for (int i = 0, j = 0; i < array.Length; i++)

            {

                if (checkElement(array [i] ))

            {

                    newMas[j] = array[i];

                    j++;

                }

            }

            return newMas;

        }

        public static int GetEvenNumbersCount(int[] a)

        {

            int count = 0;

            for (int i=0; i<a.Length; i++)

            {

                if (a[i] % 2 == 0) count++;

            }

            return count;

        }

    }

​

    public class Program

    {

        public static void Main(string[] args)

        {

            Random rnd = new Random();

            Random rndValue = new Random();

            int arrayLength = rnd.Next(5,21);

            Console.WriteLine("Количество элементов в массиве: " + arrayLength);

            int[] numbers = new int[arrayLength];

            for (int i = 0; i < numbers.Length; i++)

            numbers[i] = rndValue.Next(-100, 101);

            Methods.ShowArray(numbers);

            Methods.ShowResult(Methods.GetNegativeElements(numbers));

            Methods.ShowResult(Methods.GetMinValue(numbers));

            Methods.ShowResult(Methods.GetMaxValue(numbers));

            Methods.ShowResult(Methods.GetElementsQuantity(numbers));

            Methods.ReverseArray(numbers);

            Methods.ShowArray(numbers);

            /*int [] pozitiveNumbers = Methods.PozitiveArray(numbers);

            Methods.ShowArray(pozitiveNumbers);

            Methods.ShowResult(Methods.CountElementsSum(pozitiveNumbers));

            int[] evenNumbers = Methods.EvenNumbers(pozitiveNumbers);

            Methods.ShowArray(Methods.EvenNumbers(pozitiveNumbers));*/

            int positiveCount = Methods.GetElementsQuantity(numbers) - Methods.GetNegativeElements(numbers);

            Methods.Filter(numbers, Methods.GetEvenNumbersCount(numbers), Methods.IsEven); 

            Methods.Filter(numbers, positiveCount, a => a >= 0); 

         }

    }

}

​