using System;

using System.Collections.Generic;

using System.Linq;

using System.Diagnostics;

​

public class Program

{

    public static void Main()

    {

        List<double> powerValues = new List<double>

        {

            250.00,

            150.00,

            100.00,

            400.00,

        };

        List<double> durations = new List<double>

        {

            6100.00,

            7000.00,

            800.00,

            500.00,

        };

        Stopwatch sw = new Stopwatch();

        sw.Start();

        var result1 = CalculateCumulativeAveragePower(powerValues, durations);

        sw.Stop();

        Stopwatch sw2 = new Stopwatch();

        sw2.Start();

        var result2 = CalculateCumulativeAveragePowerWithLinq(powerValues, durations);

        sw2.Stop();

        Stopwatch sw3 = new Stopwatch();

        sw3.Start();

        var result3 = CalculateCumulativeAveragePowerFinal(powerValues, durations);

        sw3.Stop();

        Console.WriteLine("First solution:");

        Console.WriteLine("Passed tests: {0}", TestIntervalPowerCalculations(result1));

        Console.WriteLine("Elapsed First={0}\n", sw.Elapsed);

        Console.WriteLine("Second solution:");

        Console.WriteLine("Passed tests: {0}", TestIntervalPowerCalculations(result2.ToList()));

        Console.WriteLine("Elapsed Second={0}\n", sw2.Elapsed);

        Console.WriteLine("Third solution:");

        Console.WriteLine("Passed tests: {0}", TestFinalPowerCalculation(result3));

        Console.WriteLine("Elapsed Third={0}", sw3.Elapsed);

    }

​

    private static List<double> CalculateCumulativeAveragePower(List<double> powerValues, List<double> durations)

    {

        int n = powerValues.Count;

        var cumulativeAverage = new List<double>(n);

        double totalPower = 0;

        double totalTime = 0;

        for (int i = 0; i < n; i++)

        {

            totalPower += powerValues[i] * durations[i];

            totalTime += durations[i];

            cumulativeAverage.Add(totalPower / totalTime);

        }

​

        return cumulativeAverage;

    }

​

    private static IEnumerable<double> CalculateCumulativeAveragePowerWithLinq(IEnumerable<double> powerValues, IEnumerable<double> durations)

    {

        double totalPower = 0;

        double totalTime = 0;

        return powerValues.Zip(durations, CalculatePowerAverage);

        double CalculatePowerAverage(double powerValue, double durationValue)

        {

            totalPower += powerValue * durationValue;

            totalTime += durationValue;

            return totalPower / totalTime;

        }

    }

​

    private static double CalculateCumulativeAveragePowerFinal(IEnumerable<double> powerValues, IEnumerable<double> durations)

    {

        double totalTime = durations.Aggregate((runningTotal, duration) => runningTotal += duration);

        return powerValues.Zip(durations, (power, duration) => power * duration / totalTime).Sum();

    }

​

    private static bool TestIntervalPowerCalculations(List<double> powerCalculationAnswers)

    {

        List<double> expectedAnswers = new List<double>

        {

            250.00,

            196.5648854961832,

            191.0071942446043,

            198.26388888888889,

        };

        for (var i = 0; i < expectedAnswers.Count(); i++)

        {

            if (powerCalculationAnswers[i] != expectedAnswers[i])

            {

                return false;

            }

​

            continue;

        }

​

        return true;

    }

​

    private static bool TestFinalPowerCalculation(double finalPowerCalculation)

    {

        return finalPowerCalculation == 198.26388888888889;

    }

}