ArrayList.cs

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

namespace ArrayList
{
    public class ArrayList<Т> : IEnumerable<T>
    {
        //полета: елементи, брой
        private T [] elements;
        private int capacity = 2;

        //конструктор
        public ArrayList()
        {
            elements = new T[capacity];
        }

        //get и set -> по индекс от elements
        public T this[int index]
        {
            get
            {
                if (index >= capacity)
                {
                    throw new ArgumentOutOfRangeException();
                }
                return elements[index];
            }
            set
            {
                if (index >= capacity)
                {
                    throw new ArgumentOutOfRangeException();
                }
                elements[index] = value;
            }
        }

        public int Capacity
        {
            get
            {
                return capacity;
            }
            set
            {
                capacity = value;
            }
        }

        //свойства
        private void Resize()
        {
            T[] resize = new T[elements.Length * 2];
            //1. прехвърлим всички елементи от elements -> resize
            //2. elements = resize
            for (int index = 0; index < elements.Length; index++)
            {
                resize[index] = elements[index];
            }

            elements = resize;

        }

        private void Shrink()
        {
            T[] resize = new T[elements.Length / 2];
            //1. прехвърлим всички елементи от elements -> resize
            //2. elements = resize
            for (int index = 0; index < elements.Length; index++)
            {
                resize[index] = elements[index];
            }

            elements = resize;

        }

        public void Add(Т element)
        {
            //да нямаме място
            if (elements.Length == Capacity)
            {
                Resize();
            }

            //да имаме свободно място
            this.elements[this.Capacity++] = element;

        }

        public void Shift(int index)
        {
            for (int i = index; i < elements.Length; i++)
            {
                elements[i] = elements[i + 1];
            }
        }

        public T RemoveAt(int index)
        {
            if(index >= elements.Length)
            {
                throw new ArgumentOutOfRangeException();
            }

            T elementToRemove = elements[index];
            Shift(index);
            Capacity--;

            return elementToRemove;

        }

        IEnumerator<T> IEnumerable<T>.GetEnumerator()
        {
            throw new NotImplementedException();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            throw new NotImplementedException();
        }
    }

    public class T
    {
    }
}