using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var l = new List<Range> (){

            new Range(){

                Id = 1,

                Start = DateTime.Now.AddHours(1),

                End = DateTime.Now.AddHours(3)

            },

            new Range(){

                Id = 2,

                Start = DateTime.Now.AddHours(2),

                End = DateTime.Now.AddHours(6)

            },

​

            new Range(){

                Id = 3,

                Start = DateTime.Now.AddHours(6),

                End = DateTime.Now.AddHours(8)

            },

​

        };

        DetectOverlap(l);

        //Console.WriteLine("Hello World");

    }

    static void DetectOverlap(List<Range> l)

    {

        foreach(var r in l)

        {

            var overlap = l.Any(x => x.Id != r.Id 

                  && ((r.Start == x.Start && r.End == x.End) 

                      || (r.Start >= x.Start && r.Start < x.End)

                      || (r.End > x.Start && r.End <= x.End)));

            if(overlap)

            {

                Console.WriteLine("Overlap detected");

                throw new Exception("Overlapping range detected");

            }

        }

        Console.WriteLine("Clean ranges");

    }

}

​

public class Range {

    public int Id {get; set;}

    public DateTime Start {get; set;}

    public DateTime End {get; set;}

}