Get contiguous date ranges

Question

Given a list of date ranges, I'd like to get a list of contiguous date ranges.

I'm not too sure of the terminology of what I'm looking for, but I've put together a skeleton:

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;

namespace ContiguousTimeSpans
{
    class Program
    {
        static void Main(string[] args)
        {
            List<DateRange> ranges = new List<DateRange>();
            ranges.Add(new DateRange(DateTime.Parse("01/12/2015 07:00:00"), DateTime.Parse("01/12/2015 10:00:00")));
            ranges.Add(new DateRange(DateTime.Parse("01/12/2015 06:00:00"), DateTime.Parse("01/12/2015 09:00:00")));
            ranges.Add(new DateRange(DateTime.Parse("01/12/2015 05:00:00"), DateTime.Parse("01/12/2015 08:00:00")));
            ranges.Add(new DateRange(DateTime.Parse("01/12/2015 18:00:00"), DateTime.Parse("01/12/2015 21:00:00")));
            ranges.Add(new DateRange(DateTime.Parse("01/12/2015 12:00:00"), DateTime.Parse("01/12/2015 14:00:00")));
            ranges.Add(new DateRange(DateTime.Parse("01/12/2015 20:00:00"), DateTime.Parse("01/12/2015 22:00:00")));
            ranges.Add(new DateRange(DateTime.Parse("01/12/2015 11:00:00"), DateTime.Parse("01/12/2015 23:00:00")));

            List<DateRange> contiguousBlocks = GetContiguousTimespans(ranges);
            Debug.Assert(contiguousBlocks.Count == 2);

            Debug.Assert(contiguousBlocks[0].Start.Hour == 5);
            Debug.Assert(contiguousBlocks[0].End.Hour == 10);

            Debug.Assert(contiguousBlocks[1].Start.Hour == 11);
            Debug.Assert(contiguousBlocks[1].End.Hour == 23);

            Console.ReadKey();
        }

        public static List<DateRange> GetContiguousTimespans(List<DateRange> ranges)
        {
            List<DateRange> result = new List<DateRange>();
            //???
            return result;
        }
    }

    public class DateRange
    {
        public DateTime Start { get; set; }
        public DateTime End { get; set; }

        public DateRange(DateTime start, DateTime end)
        {
            Start = start;
            End = end;
        }
    }
}

Is there a way to deduce the contiguous ranges?

Answer 1

Not sure I understand this completely, but regarding what is written and the test data this should work:

public static List<DateRange> GetContiguousTimespans(List<DateRange> ranges)
{
    List<DateRange> result = new List<DateRange>();
    ranges.Sort((a,b)=>a.Start.CompareTo(b.Start));
    DateRange cur = ranges[0];

    for (int i = 1; i < ranges.Count; i++)
    {
        if (ranges[i].Start <= cur.End)
        {
            if (ranges[i].End >= cur.End)
                cur.End = ranges[i].End;
        }
        else
        {
            result.Add(cur);
            cur = ranges[i];
        }
    }

    result.Add(cur);

    return result;
}

Of course this also will need to add some checks for border values, but general idea should be clear I guess.