Found many section of times intersect (can edit), C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using System.Globalization;

namespace Rextester
{
    public class Program
    {        
        class TimeRange
        {
            public DateTime Start{get;set;} 
            public DateTime? End{get;set;} 
            public string Status{get;set;}
        }
        
        public static void Main(string[] args)
        {
            //Your code goes here
            Console.WriteLine("HoaND:_");
            var provider = new CultureInfo("de-DE");
            //var d = DateTime.ParseExact("08.05.2016", "d", provider);
            //Console.WriteLine(d);
            
            /*
            *Requirement*
            Test 1:
            => input (dd.mm.yyyy):
            t1 = 08.05.2016 -> 20.05.2016
            t2 = 17.05.2016 -> 25.05.2016
            t3 = 27.05.2016 -> 28.05.2016
            => output:
            t1 = 08.05.2016 -> 17.05.2016, Status = normal
            t2 = 17.05.2016 -> 20.05.2016, Status = overlap
            t3 = 20.05.2016 -> 25.05.2016, Status = normal
            t4 = 27.05.2016 -> 28.05.2016, Status = normal
            
            Test 2:
            => input:
            t1 = 05.05.2016 -> 20.05.2016
            t2 = 07.05.2016 -> 15.05.2016
            t3 = 17.05.2016 -> 25.05.2016
            => output:
            t1 = 05.05.2016 -> 07.05.2016, Status = normal
            t2 = 07.05.2016 -> 15.05.2016, Status = overlap
            t3 = 15.05.2016 -> 17.05.2016, Status = normal
            t4 = 17.05.2016 -> 20.05.2016, Status = overlap
            t5 = 20.05.2016 -> 25.05.2016, Status = normal
            
            Test3:
            => input:
            t1 = 05.05.2016 -> 07.05.2016
            t2 = 15.05.2016 -> 20.05.2016
            t3 = 22.05.2016 -> 25.05.2016
            => output:
            t1 = 05.05.2016 -> 07.05.2016, Status = normal
            t2 = 15.05.2016 -> 20.05.2016, Status = normal
            t3 = 22.05.2016 -> 25.05.2016, Status = normal
            */
            
            var list = new List<TimeRange>{
                new TimeRange{
                    Start = DateTime.ParseExact("05.05.2016", "d", provider),
                    End = DateTime.ParseExact("05.05.2016", "d", provider),
                    Status = ""
                },
                new TimeRange{
                    Start = DateTime.ParseExact("10.05.2016", "d", provider),
                    //End = DateTime.ParseExact("07.05.2016", "d", provider),
                    End = null,
                    Status = ""
                },
                new TimeRange{
                    Start = DateTime.ParseExact("01.05.2016", "d", provider),                    
                    End = DateTime.ParseExact("15.05.2016", "d", provider),
                    Status = ""
                }
            };
            
            ///*
            Console.WriteLine("=> Input: ");            
            foreach(var item in list){                
                Console.WriteLine(string.Format("{0} -> {1}",
                    item.Start.ToShortDateString(),
                    item.End != null ? item.End.Value.ToShortDateString() : "NULL",
                    item.Status
                   ));
            }           
            //*/
            //Logic here
            list.ForEach(x=>{
                x.End = x.End ?? DateTime.MaxValue;
            });
            var lst = new List<DateTime>();
            foreach(var item in list){                
                lst.Add(item.Start);                
                lst.Add(item.End ?? DateTime.MaxValue);
            }
            
            lst = lst.OrderBy(t=>t).ToList();
            
            /*
            foreach(var item in lst){
                Console.WriteLine(string.Format("{0}",item));
            }
            */
            
            var rs1 = new List<TimeRange>();                        
            for(var i = 1; i< lst.Count; i++){
                var temp = new TimeRange{Start = lst[i-1], End = lst[i]};
                
                var tb = temp.Start.AddDays((temp.Start.Date == temp.End.Value.Date ? 0: 1));
                
                switch(list.Where(t=> (tb >= t.Start.Date && tb <= t.End.Value.Date)).Count())
                {
                    case 0:
                        temp.Status = "blank";
                    break;
                    case 1:
                        temp.Status = "normal";
                    break;
                    default:
                        temp.Status = "overlap";
                    break;
                    
                }
                
                rs1.Add(temp);                                           
            }            
            
            rs1.RemoveAll(x=>x.Status == "blank");
            var rs2 = new List<TimeRange>();
            rs1.ForEach(x=>{
                if(rs2.Find(t=>t.Start.Date == x.Start.Date && t.End.Value.Date == x.End.Value.Date) == null){
                    rs2.Add(x);
                }
            });
            rs2.RemoveAll(x=>x.Start.Date == x.End.Value.Date 
                          && (rs2.Find(t=>t.Start.Date != t.End.Value.Date && (t.Start.Date == x.Start.Date || t.End.Value.Date == x.End.Value.Date) && t.Status == x.Status) != null));
            
            Console.WriteLine("=> Output: ");
            
            rs2.ForEach(x=>{                
                x.End = x.End == DateTime.MaxValue ? null : x.End;
            });
            
            foreach(var item in rs2){                
                Console.WriteLine(string.Format("{0} -> {1},Status={2}",
                    item.Start.ToShortDateString(),
                    item.End != null ? item.End.Value.ToShortDateString() : "NULL",
                    item.Status
                   ));
            }
        }
    }       
}

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Compilation time: 0,16 sec, absolute running time: 0,09 sec, cpu time: 0,11 sec, average memory usage: 14 Mb, average nr of threads: 3