using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        List<Tuple<DateTime, double>> list = new List<Tuple<DateTime, double>>()

        {

            new Tuple<DateTime, double>(DateTime.Now, 0.1),

            new Tuple<DateTime, double>(DateTime.Now, 0.3),

            new Tuple<DateTime, double>(DateTime.Now, 0.5),

            new Tuple<DateTime, double>(DateTime.Now, 1.1),

            new Tuple<DateTime, double>(DateTime.Now, 2.3),

            new Tuple<DateTime, double>(DateTime.Now, 3.8),

            new Tuple<DateTime, double>(DateTime.Now, 0.4),

            new Tuple<DateTime, double>(DateTime.Now, 0.7),

        };

        var result2 = list.CumulativeSum(5);

        foreach (var r in result2)

        {

            Console.WriteLine(r.Item2);

        }

        Console.WriteLine("Hello World");

    }

}

​

public static class ListTupleExtension

{

    public static List<Tuple<DateTime, double>> CumulativeSum(this List<Tuple<DateTime, double>> sequence, double limit)

    {

        List<Tuple<DateTime, double>> result = new List<Tuple<DateTime, double>>();

        double sum = 0;

        foreach(var item in sequence)

        {

            if (sum <= limit)

            {

                sum += item.Item2;

            }

            result.Add(new Tuple<DateTime, double>(item.Item1, sum));

        }

        return result;

    }

}

​