using System;

using System.Collections.Generic;

public class Program

{

    private static readonly List<int> vals = new List<int> { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

​

    public static void Main()

    {

        var t = new System.Diagnostics.Stopwatch();

        t.Start();

        var total = RunningTotal();

        Console.WriteLine(total);

        t.Stop();

        long duration = t.ElapsedMilliseconds;

        Console.WriteLine($"Normal run: {duration} ms");

        Console.WriteLine();

        Console.WriteLine();

        t = new System.Diagnostics.Stopwatch();

        t.Start();

        foreach (int e in RunningTotalYield())

        {

            Console.WriteLine(e);

        }

        t.Stop();

        duration = t.ElapsedMilliseconds;

        Console.WriteLine($"Yield run: {duration} ms");

    }

    private static int RunningTotal()

    {

        int runningTotal = 0;

​

        foreach (int val in vals)

        {

            runningTotal += val;

        }

        return runningTotal;

    }

    private static IEnumerable<int> RunningTotalYield()

    {

        int runningTotal = 0;

​

        foreach (int val in vals)

        {

            runningTotal += val;

            yield return runningTotal;

        }

    }

}

​

​