using System;
using System.Threading;
using System.Threading.Tasks;
using System.Diagnostics;

namespace zad2cw2
{
    class Program
    {
        static System.Object lck = new System.Object();
        static public ulong sum = 0;
        static public int[] tab;

        static public void randomTable(int size)
        {
            int[] tab = new int[size];

            Random randomNumber = new Random();
            Stopwatch stopwatch = new Stopwatch();

            stopwatch.Start();

            for (int i = 0; i < size; i++)
            {
                tab[i] = randomNumber.Next(0, 100);
            }

            stopwatch.Stop();

            Console.WriteLine("Time of generating of a table: " + stopwatch.ElapsedMilliseconds + " ms \n");

            normalSum(tab);
            parallelSum(tab);

        }

        static public void normalSum(int[] tab)
        {
            int sum = 0;
            Stopwatch stoper = new Stopwatch();

            stoper.Start();

            for (int i = 0; i < tab.Length; i++)
            {
                sum += tab[i];
            }

            stoper.Stop();

            Console.WriteLine("Sum sequential: " + sum);
            Console.WriteLine("Time sequential: " + stoper.ElapsedMilliseconds + " [ms]");
        }

        static public void parallelSum(int[] tab)
        {
            int sum = 0;
            Stopwatch stoper = new Stopwatch();

            stoper.Start();

            Parallel.For(0, tab.Length,
                () => 0, (j, loop, subtotal) =>
                {
                    subtotal += tab[j];
                    return subtotal;
                },
                        (x) => Interlocked.Add(ref sum, x));

            stoper.Stop();

            Console.WriteLine("Sum multithreaded: " + sum);
            Console.WriteLine("Time multithreaded: " + stoper.ElapsedMilliseconds + " [ms]");
        }

        static void Main(string[] args)
        {
            int size = 10;
            randomTable(size);

            Console.ReadKey();
        }
    }
}