using System;

using System.Collections.Generic;

using System.Linq;

​

public class Record {

  public string Name { get; set; }

  public DateTime Start { get; set; }

  public DateTime End { get; set; }

}

public class Program {

  private static IEnumerable<(TItem left, TItem right)> MyGroups<TSource, TItem>(

    IEnumerable<TSource> source, 

    Func<TSource, TItem> start, 

    Func<TSource, TItem> stop, 

    IComparer<TItem> comparer = default) {

    comparer = comparer ?? Comparer<TItem>.Default;

​

    var ordered = source

      .Where(item => comparer.Compare(start(item), stop(item)) <= 0)

      .OrderBy(item => start(item));

​

    TItem left = default;

    TItem right = default;

    bool hasRange = false;

​

    foreach (var item in ordered) {

      var currentLeft = start(item);

      var currentRight = stop(item);

​

      if (!hasRange) {

        left = currentLeft;

        right = currentRight;

        hasRange = true;

      }

      else if (comparer.Compare(right, currentLeft) >= 0) {

        right = comparer.Compare(right, currentRight) >= 0 ? right : currentRight;

        hasRange = true;

      }

      else {

        yield return (left, right);

​

        left = currentLeft;

        right = currentRight;

      }

    }

​

    if (hasRange)

      yield return (left, right);

  }

  public static void Main() {

    var records = new List<Record> {

      new Record { Name = "Group1 - A", Start = new DateTime(2024, 1, 1, 9, 0, 0), End = new DateTime(2024, 1, 1, 10, 0, 0) },

      new Record { Name = "Group1 - B", Start = new DateTime(2024, 1, 1, 9, 30, 0), End = new DateTime(2024, 1, 1, 11, 0, 0) },

      new Record { Name = "Group1 - C", Start = new DateTime(2024, 1, 1, 10, 30, 0), End = new DateTime(2024, 1, 1, 12, 0, 0) },

      new Record { Name = "Group2 - D", Start = new DateTime(2024, 1, 1, 13, 0, 0), End = new DateTime(2024, 1, 1, 15, 0, 0) },

      new Record { Name = "Group3 - E", Start = new DateTime(2024, 1, 2, 22, 0, 0), End = new DateTime(2024, 1, 2, 23, 0, 0) },

      new Record { Name = "Group3 - F", Start = new DateTime(2024, 1, 2, 22, 30, 0), End = new DateTime(2024, 1, 3, 5, 0, 0) }

   };

​

   var result = MyGroups(records, rec => rec.Start, rec => rec.End);

​

   var report = string.Join(Environment.NewLine, result

     .Select((item, index) => $"Group {index + 1} - Start: {item.left:d/M/yyyy htt}, End: {item.right:d/M/yyyy htt}"));

    Console.WriteLine(report);

  }

}