C# Online Compiler | .NET Fiddle

<no name> by Anonymous

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

class Solution
{
    class Ticket {
        /// <summary>
        /// A short description of this ticket
        /// </summary>
        public string Title { get; set; }

        /// <summary>
        /// The date the ticket was open or created
        /// </summary>
        public DateTime CreatedAt { get ; set; }

        /// <summary>
        /// The current state of the ticket
        /// </summary>
        public ResolutionState Status { get ; set; }

        /// <summary>
        /// Any additional tickets that this ticket is dependent on. A subticket will not have a
        /// circular dependency on any of its parent tickets 
        /// </summary>
        public IEnumerable<Ticket> SubTickets { get; set; }

        /// <summary>
        /// Return the collection of tickets that have been open for too long. Include
        /// any <see cref="SubTickets"/> that are overdue as well
        /// </summary>
        /// 
        /// <param name="tickets"> a collection of tickets to inspect; they may have
        /// related subtickets; they may also be closed</param>
        /// 
        /// <param name="cutoff"> "staleness" threshold date; unclosed tickets created on or before
        /// this date are considered to be overdue</param>
        /// 
        /// <returns> a collection of unclosed tickets created on or before the cutoff date</returns>
        public static IEnumerable<Ticket> GetOverdue(IEnumerable<Ticket> tickets, DateTime cutoff) {
			return FilterTickets(tickets, x => x.Status != ResolutionState.Closed && x.CreatedAt <= cutoff);
        }
		
		public static IEnumerable<Ticket> FilterTickets(IEnumerable<Ticket> tickets, Func<Ticket, bool> predicate)
		{
			predicate ??= x => true;
			return
				default == tickets ? Enumerable.Empty<Ticket>()
				: tickets.Where(predicate).Concat(tickets.SelectMany(x => FilterTickets(x.SubTickets, predicate)));
		}
    }


    enum ResolutionState {
        Opened,
        Assigned,
        Closed,
        Blocked
    }

    static void Main(string[] args)
    {
        var priya = TestData.OnboardPriya();
        var marcus = TestData.OnboardMarcus();
        var carly = TestData.OnboardCarly();

        var tickets = new Ticket[] {priya, marcus, carly};
        var cutoff = DateTime.Today.AddDays(-7);

        var overdue = Ticket.GetOverdue(tickets, cutoff);

        if (overdue == null) {
            Console.Error.WriteLine("null overdue");
            return;
        }
        if (overdue.Count() != TestData.OverdueTitles.Count()) {
            Console.Error.WriteLine("incorrect count");
        }

        foreach (var expired in TestData.OverdueTitles) {
            if (!overdue.Any(t => t.Title == expired)) {
                Console.Error.WriteLine($"missing {expired}");
            }        
        }
        Console.WriteLine("Finished");
    }
    
    static class TestData
    {
        public static Ticket OnboardPriya()
        {
            return new Ticket
            {
                Title = "Onboard Priya",
                CreatedAt = DateTime.Today.AddDays(-10),
                Status = ResolutionState.Opened,
                SubTickets = new[]
                {
                    new Ticket
                    {
                        Title = "Network Access for Priya",
                        CreatedAt = DateTime.Today.AddDays(-8),
                        Status = ResolutionState.Assigned,
                        SubTickets = new[]
                        {
                            new Ticket
                            {
                                Title = "AWS access for Priya",
                                CreatedAt = DateTime.Today.AddDays(-4),
                                Status = ResolutionState.Assigned

                            },
                            new Ticket
                            {
                                Title = "VPN Access for Priya",
                                CreatedAt = DateTime.Today.AddDays(-8),
                                Status = ResolutionState.Assigned,
                                SubTickets = new[]
                                {
                                  new Ticket 
                                  {
                                    Title = "VPN 2FA acquired",
                                    CreatedAt = DateTime.Today.AddDays(-8),
                                    Status = ResolutionState.Blocked
                                  }
                                }
                            }
                        },
                    },
                    new Ticket
                    {
                        Title = "Desk Setup for Priya",
                        CreatedAt = DateTime.Today.AddDays(-9),
                        Status = ResolutionState.Closed
                    },
                    new Ticket
                    {
                        Title = "Laptop for Priya",
                        CreatedAt = DateTime.Today.AddDays(-10),
                        Status = ResolutionState.Assigned
                    }
                }
            };
        }

        public static Ticket OnboardMarcus()
        {
            return new Ticket
            {
                Title = "Onboard Marcus",
                CreatedAt = DateTime.Today.AddDays(-12),
                Status = ResolutionState.Assigned,
                SubTickets = new[]
                {
                    new Ticket
                    {
                        Title = "Network Access for Marcus",
                        CreatedAt = DateTime.Today.AddDays(-10),
                        Status = ResolutionState.Closed,
                        SubTickets = new[]
                        {
                            new Ticket
                            {
                                Title = "AWS access for Marcus",
                                CreatedAt = DateTime.Today.AddDays(-9),
                                Status = ResolutionState.Closed
                            },
                            new Ticket
                            {
                                Title = "VPN Access for Marcus",
                                CreatedAt = DateTime.Today.AddDays(-10),
                                Status = ResolutionState.Closed
                            }
                        }
                    },
                    new Ticket
                    {
                        Title = "Desk Setup for Marcus",
                        CreatedAt = DateTime.Today.AddDays(-10),
                        Status = ResolutionState.Opened
                    },
                    new Ticket
                    {
                        Title = "Laptop for Marcus",
                        CreatedAt = DateTime.Today.AddDays(-8),
                        Status = ResolutionState.Closed,
                    }
                }
            };
        }

        public static Ticket OnboardCarly()
        {
            return new Ticket
            {
                Title = "Onboard Carly",
                CreatedAt = DateTime.Today.AddDays(-6),
                Status = ResolutionState.Assigned,
                SubTickets = new[]
                {
                    new Ticket
                    {
                        Title = "Network Access for Carly",
                        CreatedAt = DateTime.Today.AddDays(-6),
                        Status = ResolutionState.Closed,
                        SubTickets = new[]
                        {
                            new Ticket
                            {
                                Title = "AWS access for Carly",
                                CreatedAt = DateTime.Today.AddDays(-6),
                                Status = ResolutionState.Closed
                            },
                            new Ticket
                            {
                                Title = "VPN Access for Carly",
                                CreatedAt = DateTime.Today.AddDays(-6),
                                Status = ResolutionState.Assigned
                            }
                        }
                    },
                    new Ticket
                    {
                        Title = "Desk Setup for Carly",
                        CreatedAt = DateTime.Today.AddDays(-6),
                        Status = ResolutionState.Closed
                    },
                    new Ticket
                    {
                        Title = "Laptop for Carly",
                        CreatedAt = DateTime.Today.AddDays(-5),
                        Status = ResolutionState.Assigned,
                    }
                }
            };
        }


        public static IEnumerable<string> OverdueTitles = new [] {
            "Onboard Priya",
            "Network Access for Priya",
            "VPN Access for Priya",
            "Laptop for Priya",
            "Onboard Marcus",
            "Desk Setup for Marcus",
            "VPN 2FA acquired",     
        };     
    }
}

​x
 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Diagnostics;
​
class Solution
{
    class Ticket {
        /// <summary>
        /// A short description of this ticket
        /// </summary>
        public string Title { get; set; }
​
        /// <summary>
        /// The date the ticket was open or created
        /// </summary>
        public DateTime CreatedAt { get ; set; }
​
        /// <summary>
        /// The current state of the ticket
        /// </summary>
        public ResolutionState Status { get ; set; }
​
        /// <summary>
        /// Any additional tickets that this ticket is dependent on. A subticket will not have a
        /// circular dependency on any of its parent tickets 
        /// </summary>
        public IEnumerable<Ticket> SubTickets { get; set; }
​
        /// <summary>
        /// Return the collection of tickets that have been open for too long. Include
        /// any <see cref="SubTickets"/> that are overdue as well
        /// </summary>
        /// 
        /// <param name="tickets"> a collection of tickets to inspect; they may have
        /// related subtickets; they may also be closed</param>
        /// 
        /// <param name="cutoff"> "staleness" threshold date; unclosed tickets created on or before
        /// this date are considered to be overdue</param>
        /// 
        /// <returns> a collection of unclosed tickets created on or before the cutoff date</returns>
        public static IEnumerable<Ticket> GetOverdue(IEnumerable<Ticket> tickets, DateTime cutoff) {
            return FilterTickets(tickets, x => x.Status != ResolutionState.Closed && x.CreatedAt <= cutoff);
        }
        
        public static IEnumerable<Ticket> FilterTickets(IEnumerable<Ticket> tickets, Func<Ticket, bool> predicate)
        {
            predicate ??= x => true;
            return
                default == tickets ? Enumerable.Empty<Ticket>()
                : tickets.Where(predicate).Concat(tickets.SelectMany(x => FilterTickets(x.SubTickets, predicate)));
        }
    }
​
​
    enum ResolutionState {
        Opened,
        Assigned,
        Closed,
        Blocked
    }
​
    static void Main(string[] args)
    {
        var priya = TestData.OnboardPriya();
        var marcus = TestData.OnboardMarcus();
        var carly = TestData.OnboardCarly();
​
        var tickets = new Ticket[] {priya, marcus, carly};
        var cutoff = DateTime.Today.AddDays(-7);
​
        var overdue = Ticket.GetOverdue(tickets, cutoff);
​
        if (overdue == null) {
            Console.Error.WriteLine("null overdue");
            return;
        }
        if (overdue.Count() != TestData.OverdueTitles.Count()) {
            Console.Error.WriteLine("incorrect count");
        }
​
        foreach (var expired in TestData.OverdueTitles) {
            if (!overdue.Any(t => t.Title == expired)) {
                Console.Error.WriteLine($"missing {expired}");
            }        
        }
        Console.WriteLine("Finished");
    }
    
    static class TestData
    {
        public static Ticket OnboardPriya()
        {
            return new Ticket
            {
                Title = "Onboard Priya",
                CreatedAt = DateTime.Today.AddDays(-10),
                Status = ResolutionState.Opened,
                SubTickets = new[]
                {
                    new Ticket
                    {
                        Title = "Network Access for Priya",
                        CreatedAt = DateTime.Today.AddDays(-8),
                        Status = ResolutionState.Assigned,
                        SubTickets = new[]
                        {
                            new Ticket
                            {
                                Title = "AWS access for Priya",
                                CreatedAt = DateTime.Today.AddDays(-4),
                                Status = ResolutionState.Assigned
​
                            },
                            new Ticket
                            {
                                Title = "VPN Access for Priya",
                                CreatedAt = DateTime.Today.AddDays(-8),
                                Status = ResolutionState.Assigned,
                                SubTickets = new[]
                                {
                                  new Ticket 
                                  {
                                    Title = "VPN 2FA acquired",
                                    CreatedAt = DateTime.Today.AddDays(-8),
                                    Status = ResolutionState.Blocked
                                  }
                                }
                            }
                        },
                    },
                    new Ticket
                    {
                        Title = "Desk Setup for Priya",
                        CreatedAt = DateTime.Today.AddDays(-9),
                        Status = ResolutionState.Closed
                    },
                    new Ticket
                    {
                        Title = "Laptop for Priya",
                        CreatedAt = DateTime.Today.AddDays(-10),
                        Status = ResolutionState.Assigned
                    }
                }
            };
        }
​
        public static Ticket OnboardMarcus()
        {
            return new Ticket
            {
                Title = "Onboard Marcus",
                CreatedAt = DateTime.Today.AddDays(-12),
                Status = ResolutionState.Assigned,
                SubTickets = new[]
                {
                    new Ticket
                    {
                        Title = "Network Access for Marcus",
                        CreatedAt = DateTime.Today.AddDays(-10),
                        Status = ResolutionState.Closed,
                        SubTickets = new[]
                        {
                            new Ticket
                            {
                                Title = "AWS access for Marcus",
                                CreatedAt = DateTime.Today.AddDays(-9),
                                Status = ResolutionState.Closed
                            },
                            new Ticket
                            {
                                Title = "VPN Access for Marcus",
                                CreatedAt = DateTime.Today.AddDays(-10),
                                Status = ResolutionState.Closed
                            }
                        }
                    },
                    new Ticket
                    {
                        Title = "Desk Setup for Marcus",
                        CreatedAt = DateTime.Today.AddDays(-10),
                        Status = ResolutionState.Opened
                    },
                    new Ticket
                    {
                        Title = "Laptop for Marcus",
                        CreatedAt = DateTime.Today.AddDays(-8),
                        Status = ResolutionState.Closed,
                    }
                }
            };
        }
​
        public static Ticket OnboardCarly()
        {
            return new Ticket
            {
                Title = "Onboard Carly",
                CreatedAt = DateTime.Today.AddDays(-6),
                Status = ResolutionState.Assigned,
                SubTickets = new[]
                {
                    new Ticket
                    {
                        Title = "Network Access for Carly",
                        CreatedAt = DateTime.Today.AddDays(-6),
                        Status = ResolutionState.Closed,
                        SubTickets = new[]
                        {
                            new Ticket
                            {
                                Title = "AWS access for Carly",
                                CreatedAt = DateTime.Today.AddDays(-6),
                                Status = ResolutionState.Closed
                            },
                            new Ticket
                            {
                                Title = "VPN Access for Carly",
                                CreatedAt = DateTime.Today.AddDays(-6),
                                Status = ResolutionState.Assigned
                            }
                        }
                    },
                    new Ticket
                    {
                        Title = "Desk Setup for Carly",
                        CreatedAt = DateTime.Today.AddDays(-6),
                        Status = ResolutionState.Closed
                    },
                    new Ticket
                    {
                        Title = "Laptop for Carly",
                        CreatedAt = DateTime.Today.AddDays(-5),
                        Status = ResolutionState.Assigned,
                    }
                }
            };
        }
​
​
        public static IEnumerable<string> OverdueTitles = new [] {
            "Onboard Priya",
            "Network Access for Priya",
            "VPN Access for Priya",
            "Laptop for Priya",
            "Onboard Marcus",
            "Desk Setup for Marcus",
            "VPN 2FA acquired",     
        };     
    }
}

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