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C# arrange the items by matching start and end value

I have a input in this way,
Start= 2, End= 3
Start= 6, End= 7
Start= 3, End= 4
Start= 0, End= 1
Start= 4, End= 5
Start= 1, End= 2
Start= 6, End= 7
where I have to display the output that are sorted by their matching start- and end values. The first element are the object whose Start doesn't have any matching End values, and after that the records(Start) have the matching end values.
I needed to have the output in the following ways:
Start = 0, End = 1
Start = 1, End = 2
Start = 2, End = 3
Start = 3, End = 4
Start = 4, End = 5
Start = 5, End = 6
Start = 6, End = 7
What I have tried so far:
Created a List of Inputs
var inputs = new List
{
new Input{Start = 2, End = 3},
new Input{Start = 6, End = 7},
new Input{Start = 3, End = 4},
new Input{Start = 0, End = 1},
new Input{Start = 5, End = 6},
new Input{Start = 4, End = 5},
new Input{Start = 1, End = 2}
};
Get the list of all the Ends
var ends = inputs.Select(t => t.End);
Filter from the input where value of End matched with the Start of the next Objects.
var filtered = inputs.Where(t => ends.Any(to => to == t.Start)).ToList();
Get the list where Start doesn't have the matching ends:
var output = inputs.Where(t => !ends.Any(to => to == t.Start)).ToList();
Now filter the results as:
while (filtered.Count != 0)
{
var outs = filtered.Where(i => output.Any(l => i.Start == l.End)).FirstOrDefault();
output.Add(outs);
filtered.Remove(outs);
}
foreach (Input s in output)
{
Console.WriteLine($"Start = {s.Start}, End = {s.End}");
}
Dotnet fiddle:
I have somehow able to solve this problem with this approach. But I have a doubt that this is not a proper ways of solving. Because I have a repetitive filter for getting the matched and unmatched records and, I have also a doubt on the while loop implementation.
Any suggestion for a better approach of solving this problem?

If the End is always equals Start + 1. Then, you could take the max value of Start and with a simple for loop, you check, if exists, return value, if not, insert the new value.
Here is an extension method that would accept almost all type of collections or arrays :
public static class Extensions
{
public static IEnumerable<Input?> SortAndFill(this IEnumerable<Input?> source)
{
if(source == null) yield break;
var max = source?.Max(x=> x.Start) ?? 0;
if (max == 0) yield break;
max++;
for (int x = 0; x < max; x++)
{
var item = source.FirstOrDefault(s => s.Start == x);
if (item == null)
item = new Input(x, x + 1);
yield return item;
}
}
}
usage :
var result = inputs.SortAndFill().ToArray();

Reversing a list of objects with a timespan property, while maintaining the time difference between the objects

I'd like to reverse a list of objects with a TimeSpan property, which should maintain it's TimeSpan difference when reversing.
To give an example, consider a route from A to D with the following TimeSpans:
(A 12:00), (B 12:15), (C 12:40), (D 13:40).
Between A and B there is a 15 minute difference, between B and C there is a 25 minute difference and so on. I'd like to reverse this list in an efficient manner, where the result list would look like:
(D: 12:00), (C 13:00), (B 13:25), (A 13:40).
My first idea was creating a list of time differences and using that and the start time to create the new objects with the correct times, however I feel like the solution could be better.
Edit: Added my (working) sample solution. Any feedback is appreciated.
private IList<Activity> ReverseActivities(IList<Activity> activities)
{
IList<TimeSpan> timeDifferences = GetTimeDifferences(activities);
IList<Activity> resultList = new List<Activity>();
TimeSpan timeOfDay = activities.First().TimeOfDay;
for (int i = activities.Count - 1; i >= 0; i--)
{
resultList.Add(new Activity(activities[i].Name, timeOfDay));
timeOfDay = timeOfDay.Add(timeDifferences[i]);
}
return resultList;
}
private IList<TimeSpan> GetTimeDifferences(IList<Activity> activities)
{
IList<TimeSpan> timeDifferences = new List<TimeSpan>();
Activity prev = activities.First();
if (activities.Count > 1)
{
foreach (var curr in activities)
{
timeDifferences.Add(curr.TimeOfDay - prev.TimeOfDay);
prev = curr;
}
}
return timeDifferences;
}
Activity looks as follows:
public class Activity
{
public Activity(string name, TimeSpan timeOfDay)
{
this.Name = name;
this.TimeOfDay = timeOfDay;
}
public string Name { get; }
public TimeSpan TimeOfDay { get; }
}

One trick we can use is to have a single loop that finds the corresponding item from the end of the list based on the current index. We can do this like:
for (int i = 0; i < activities.Count; i++)
var correspondingIndex = activities.Count - i - 1;
Notice that:
When i is 0, correspondingIndex is the last index in the array.
When i is 1, correspondingIndex is the second-to-last index in the array.
When i is activities.Count - 1 (the last index), correspondingIndex is 0
Using this trick, we can get the corresponding time differences at the same time as we populate a new list of Activity objects.
Hopefully this code makes it a little clearer:
public static IList<Activity> ReverseActivities(IList<Activity> activities)
{
// If activities is null or contains less than 2 items, return it
if ((activities?.Count ?? 0) < 2) return activities;
// This will contain the reversed list
var reversed = new List<Activity>();
for (int i = 0; i < activities.Count; i++)
{
// Get the corresponding index from the end of the list
var correspondingIndex = activities.Count - i - 1;
// Get the timespan from the corresponding items from the end of the list
var timeSpan = i == 0
? TimeSpan.Zero
: activities[correspondingIndex + 1].TimeOfDay -
activities[correspondingIndex].TimeOfDay;
// The new TimeOfDay will be the previous item's TimeOfDay plus the TimeSpan above
var timeOfDay = i == 0
? activities[i].TimeOfDay
: reversed[i - 1].TimeOfDay + timeSpan;
reversed.Add(new Activity(activities[correspondingIndex].Name, timeOfDay));
}
return reversed;
}
In use, this would look like:
var original = new List<Activity>
{
new Activity("A", new TimeSpan(0, 12, 0)),
new Activity("B", new TimeSpan(0, 12, 15)),
new Activity("C", new TimeSpan(0, 12, 40)),
new Activity("D", new TimeSpan(0, 13, 40))
};
var reversed = ReverseActivities(original);
Here's the output in the debug window (compare original and reversed):

This is quite simple using a bit of TimeSpan maths.
IList<Activity> input = new List<Activity>()
{
new Activity("A", TimeSpan.Parse("12:00")),
new Activity("B", TimeSpan.Parse("12:15")),
new Activity("C", TimeSpan.Parse("12:40")),
new Activity("D", TimeSpan.Parse("13:40")),
};
TimeSpan min = input.Min(x => x.TimeOfDay);
TimeSpan max = input.Max(x => x.TimeOfDay);
IList<Activity> output =
input
.Select(x => new Activity(
x.Name,
x.TimeOfDay.Subtract(max).Duration().Add(min)))
.OrderBy(x => x.TimeOfDay)
.ToList();
That gives me:

I tested this and it works:
DateTime[] times = { new DateTime(2020, 06, 17, 12, 00, 00),
new DateTime(2020, 06, 17, 12, 15, 00), new DateTime(2020, 06, 17, 12, 40, 00),
new DateTime(2020, 06, 17, 13, 40, 00) };
List<DateTime> newTimes = new List<DateTime>();
newTimes.Add(times[0]);
for (int i = 1; i < times.Length; i++) {
DateTime d = newTimes[i - 1].Add(times[times.Length - i] - times[times.Length - i - 1]);
newTimes.Add(d);
}

Using LinkedList:
static void Main(string[] args)
{
var list = new List<Location>
{
new Location{Name = "A", TimeOffset = DateTimeOffset.MinValue.Add(new TimeSpan(12, 0, 0)) },
new Location{Name = "B", TimeOffset = DateTimeOffset.MinValue.Add(new TimeSpan(12, 15, 0)) },
new Location{Name = "C", TimeOffset = DateTimeOffset.MinValue.Add(new TimeSpan(12, 40, 0)) },
new Location{Name = "D", TimeOffset = DateTimeOffset.MinValue.Add(new TimeSpan(13, 40, 0)) },
};
var route = new LinkedList<Location>(list);
WriteToConsole("Before: ", route);
var reversedRoute = Reverse(route);
Console.WriteLine();
WriteToConsole("After: ", reversedRoute);
Console.WriteLine(); Console.ReadKey();
}
public static LinkedList<Location> Reverse(LinkedList<Location> route)
{
LinkedList<Location> retVal = new LinkedList<Location>();
DateTimeOffset timeOffset = DateTimeOffset.MinValue;
var currentNode = route.Last;
while (currentNode != null)
{
var next = currentNode.Next;
if (next == null)
{
// last node, use the first node offset
timeOffset = DateTimeOffset.MinValue.Add(route.First.Value.TimeOffset - timeOffset);
}
else
{
timeOffset = timeOffset.Add(next.Value.TimeOffset - currentNode.Value.TimeOffset);
}
retVal.AddLast(new Location { Name = currentNode.Value.Name, TimeOffset = timeOffset });
currentNode = currentNode.Previous;
}
return retVal;
}
public static void WriteToConsole(string title, LinkedList<Location> route)
{
Console.Write($"{title}: ");
foreach (var i in route)
{
Console.Write($"\t({i.Name}, {i.TimeOffset.Hour:D2}:{i.TimeOffset.Minute:D2})");
}
}

how do I ask an if argument on a specific field which in a list of objects that contain a list in c#?

I have a list of objects in which every object is containing a list itself. how do I get the the JellyFishID field or the Amount field for using an IF argument
(I'm currently using Foreach):`
public static List<Report> DataSorted = new List<Report> {
new Report() { IsGoldUser=true, Date=new DateTime(2016, 3, 12,11, 59, 33), IsBurningWater=true, Type=Type.Shore, ZoneID = 1 ,
ReportDetails =new List<ReportDetail> { new ReportDetail() { Amount = Amount.Few, Jellyfish = new Jellyfish { JellyfishID = 1, Venom = Venom.Strong } } } },
new Report() { IsGoldUser=true, Date=new DateTime(2016, 3, 12, 11, 59, 33), IsBurningWater=true, Type=Type.Shore, ZoneID = 1 ,
ReportDetails =new List<ReportDetail> { new ReportDetail() { Amount = Amount.Few, Jellyfish = new Jellyfish { JellyfishID = 1, Venom = Venom.Strong } } } },
new Report() { IsGoldUser=true, Date=new DateTime(2016, 3, 12, 11, 59, 33), IsBurningWater=true, Type=Type.Shore, ZoneID = 1 ,
ReportDetails =new List<ReportDetail> { new ReportDetail() { Amount = Amount.Few, Jellyfish = new Jellyfish { JellyfishID = 1, Venom = Venom.Strong } } } },
new Report() { IsGoldUser=true, Date=new DateTime(2016, 3, 12, 11, 59, 33), IsBurningWater=true, Type=Type.Shore, ZoneID = 1 ,
ReportDetails =new List<ReportDetail> { new ReportDetail() { Amount = Amount.Few, Jellyfish = new Jellyfish { JellyfishID = 1, Venom = Venom.Strong } } } },
foreach (var item in DataSorted)
{
if (item.ReportDetails....) //???I want here to Make an Argument about The Amount field or the JellyFishID field in the list above....
}

You don't describe exactly what you want to check, but with LINQ to Objects you have a lot of possiblities. At first, you need to reference the correct namespace with
using System.Linq;
at the top of your source code file.
Now, if you want to check if any items of your list contains a jellyfish with a given ID, you can use:
if (item.ReportDetails.Any(t => t.Jellyfish.JellyfishID == 1)) //...
Additionally you can have conditions inside a Where-function to filter your list and search only for jellyfish with a few amount:
if (item.ReportDetails.Where(t => t.Amount == Amount.Few).
Any(t => t.Jellyfish.JellyfishID == 1)) //...
There is a lot of information avaliable about LINQ, a lot of examples are in the MSDN (for example this intro page), but there are alternatives like this one: 101 Linq examples. It even has a tag on StackOverflow.

List with dates, addHours to list linq

I have a List with dates to show it in a grid and I would like add one hour to range2:
private void grid_loaded(object sender, RoutedEventArgs e)
{
var data = new List<EntityViewModel>
{
new EntityViewModel { aDay = new DateTime(1980, 1, 1, 12, 0, 12) },
new EntityViewModel { aDay = new DateTime(1983, 1, 1, 12, 23, 12) },
new EntityViewModel { aDay = new DateTime(1985, 6, 14, 12, 0, 12) },
new EntityViewModel { aDay = new DateTime(1990, 7, 3, 12, 23, 12) },
new EntityViewModel { aDay = new DateTime(1995, 8, 1, 4, 23, 12) },
new EntityViewModel { aDay = new DateTime(1996, 1, 1, 12, 0, 12) },
new EntityViewModel { aDay = new DateTime(2000, 1, 1, 12, 0, 12) },
new EntityViewModel { aDay = DateTime.Now }
};
var range = data.Where(i => i.aDay.Year >= 1983 && i.aDay.Year <= 1996).ToList();
var range2 = range.Where(i => i.aDay.Date.IsDaylightSavingTime() == true).ToList();
}
I tried this:
var range3 = range.Where(i => i.aDay.Date.IsDaylightSavingTime() == true).ToList();
range3.ForEach(i => i.aDay.AddHours(1));
this:
foreach (var item in range2.Where(x => x.aDay != null))
{
item.aDay.AddHours(1);
}
and this:
var range5 = range2.Where(i => i.aDay != null).Select(i => { i.aDay.AddHours(1); return i; }).ToList();
But it doesn't do anything, are always the same hour.

AddHours does NOT alter the initial date, but return a new one.
You need to select these dates:
var range5 = range2.Where(i => i.aDay != null).Select(i => i.aDay.AddHours(1));
To get the altered dates or
range3.ForEach(i => i.aDay = i.aDay.AddHours(1));
To alter the dates of the items in the list.

DateTime is a structure, so you have to do:
var date = DateTime.Now;
date = date.AddHours(1);
in your case:
range3.ForEach(i => i.aDay = i.aDay.AddHours(1));

AddHours returns a new DateTime, it does not change the current instance.
http://msdn.microsoft.com/en-us/library/system.datetime.addhours.aspx
for (int i = 0; i < range2.Count; ++i) {
range2[i].aDay = range2[i].aDay.AddHours(1);
}

DateTime Ticks, check for overlapping dates C#

Lets say I 2 longs a start and end, which are really two date times converted to ticks. How would I tell if these two values overlap?

As MPelletier mentioned: you need two pairs of DateTimes:
var start1 = new DateTime(2013, 4, 10).Ticks;
var end1 = new DateTime(2013, 4, 20).Ticks;
var start2 = new DateTime(2013, 4, 9).Ticks;
var end2 = new DateTime(2013, 4, 11).Ticks;
if (start2 < end1)
{
//// Overlapping
}