using System;

using System.Linq;

using System.Threading;

​

namespace factorial

{

    public class MainClass

    {

        public static void Main(string[] args)

        {

            int[] factorials = { 3, 4, 5, 1, 3, 4, 5, 1, 3, 4, 5, 1, 3, 4, 5, 1, 3, 4 };

​

            CountFactorial countFactorial = new CountFactorial(factorials);

​

            DateTime timeStart = DateTime.Now;

            countFactorial.SetSumFactorialByOneThread();

            DateTime timeEnd = DateTime.Now;

            countFactorial.SetSumFactorialByThreads();

            DateTime timeEnd2 = DateTime.Now;

​

            Console.WriteLine(string.Format("Normal sum = {0}, time = {1} ns", countFactorial.firstWayCount, timeEnd - timeStart));

            Console.WriteLine(string.Format("Threaded sum = {0}, time = {1} ns", countFactorial.secondWayCount, timeEnd2 - timeEnd));

        }

    }

​

    class CountFactorial

    {

        private int[] factorials;

        public int firstWayCount;

        public int secondWayCount;

​

        public CountFactorial(int[] factorials)

        {

            this.factorials = factorials;

        }

​

        public void SetSumFactorialByOneThread()

        {

            firstWayCount = GetSumFactorial(factorials);  

        }

​

        public void SetSumFactorialByThreads()

        {

            //делим массив на 4 массива

            int rangeArr1 = 4;

            int rangeArr2 = 4;

            int rangeArr3 = 4;

            int rangeArr4 = 6;

​

            var arr1 = factorials.Take(rangeArr1).ToArray();

            var arr2 = factorials.Skip(rangeArr1).Take(rangeArr2).ToArray();

            var arr3 = factorials.Skip(rangeArr1 + rangeArr2).Take(rangeArr3).ToArray();

            var arr4 = factorials.Skip(rangeArr1 + rangeArr2 + rangeArr3).Take(rangeArr4).ToArray();

​

            // запускаем 4 массива для расчета факториала

            StartTheThread(arr1);

            StartTheThread(arr2);

            StartTheThread(arr3);

            StartTheThread(arr4);

        }

​

        public void StartTheThread(int[] factorials)

        {

            Thread thread = new Thread(() => { secondWayCount += GetSumFactorial(factorials); });

​

            thread.Start();

            thread.Join();

        }

​

        private int GetSumFactorial(int[] factorials)

        {

            int sum = 0;

            foreach (int factorialLength in factorials)

            {

                int factorial = 1;

                for (int i = 1; i <= factorialLength; i++)

                {

                    factorial *= i;

                    Thread.Sleep(10);

                }

                sum += factorial;

            }

​

            return sum;

        }

    }

}