How to fix the program (shaker sort)?

Question

Algorithms

Help me figure it out, on line 28, where the first for loop of the algorithm itself begins, it gives an error that the index is out of scope of the array:

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

namespace BubbleSort
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] a = new int[5];
            int i = 0, left = 0, right = 4, last = 5, z;
            Random random = new Random();
            for (i = 0; i < a.Length; i++)
            {
                a[i] = 0 + random.Next(100);
            }
            foreach (int element in a)
                Console.Write(element + " ");
            Console.WriteLine();

            while (left < right)
            {
                for (i = right; i >= left; i--) //здесь ошибка
                {
                    if (a[i - 1] > a[i])
                    {
                        z = a[i - 1];
                        a[i] = a[i - 1];
                        a[i - 1] = z;
                        last = i;
                    }
                }
                left = last + 1;
                for (i = left; i < right; i++)
                {
                    if (a[i - 1] > a[i])
                    {
                        z = a[i - 1];
                        a[i] = a[i - 1];
                        a[i - 1] = z;
                    }
                }
                right = last - 1;
            }
            foreach (int element in a)
                Console.Write(element + " ");
            Console.ReadKey();
        }
    }
}

Answer 1

Try i > left. Otherwise, with i=0, you get access to a non-existent element a[-1]