[C#] 無聊寫的linq 範例

//Rextester.Program.Main is the entry point for your code. Don't change it.

//Microsoft (R) Visual C# Compiler version 2.9.0.63208 (958f2354)

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text.RegularExpressions;

namespace Rextester

{

    public enum DirTypeEnum

    {

        TopDir = 0,

        SubDir = 1

    }

    

    public class TestData

    {

        public int Id {get; set;}

        public int IsUsing {get; set;} 

        public string Name {get; set;}

        public DirTypeEnum Type {get; set;}

        public int? Parent {get; set;}

    }

    

    public class Program

    {

        public static void Main(string[] args)

        {

            var data = new List<TestData>();

            data.Add(new TestData {Id = 0, IsUsing = 1, Name = "Top Dir1", Type = DirTypeEnum.TopDir, Parent = null});

            data.Add(new TestData {Id = 1, IsUsing = 0, Name = "Sub Dir 1", Type = DirTypeEnum.SubDir, Parent = 0});

            data.Add(new TestData {Id = 2, IsUsing = 1, Name = "Sub Dir 2", Type = DirTypeEnum.SubDir, Parent = 0});

            data.Add(new TestData {Id = 3, IsUsing = 1, Name = "Top Dir2", Type = DirTypeEnum.TopDir, Parent = null});

            data.Add(new TestData {Id = 4, IsUsing = 0, Name = "Sub Dir 1", Type = DirTypeEnum.SubDir, Parent = 3});

            

            var topDir = data.Where(o=>o.Type == DirTypeEnum.TopDir).ToList();

            topDir.Select(x => {

                x.IsUsing = (data.Where(p => p.Parent== x.Id).Sum(l => l.IsUsing) >= 1?1:0);

                return x;

            }).ToList();

           

            foreach(var x in data)

            {

                Console.WriteLine($"Id = {x.Id}, IsUsing = {x.IsUsing}, Name = {x.Name}, Type = {x.Type}, Parent = {x.Parent}");

            }

        }

    }

}