添加项目文件。

LeetCodeSharp.Fetcher/Fetcher.cs

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+using System.Net.Http.Json;
+using System.Text.Json;
+using LeetCodeSharp.Fetcher.Models;
+
+namespace LeetCodeSharp.Fetcher;
+
+internal class Fetcher
+{
+    private const string ProblemsUrl = "https://leetcode.cn/api/problems/algorithms/";
+    private const string GraphQlUrl = "https://leetcode.cn/graphql";
+
+    private readonly HttpClient _httpClient = new();
+
+    private readonly JsonSerializerOptions _serializerOptions = new()
+    {
+        PropertyNameCaseInsensitive = true,
+        PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower
+    };
+
+    public async Task<Problems> GetProblems()
+    {
+        var problems =
+            await _httpClient.GetFromJsonAsync<Problems>(ProblemsUrl, _serializerOptions)
+                ?? throw new Exception("Failed to get problems.");
+
+        return problems;
+    }
+
+    public async Task<Problem> GetProblem(uint questionId)
+    {
+        var problems = await GetProblems();
+
+        var targetProblem = problems.StatStatusPairs.First(p =>
+        {
+            if (uint.TryParse(p.Stat.FrontendQuestionId, out var id))
+            {
+                return id == questionId;
+            }
+
+            return false;
+        });
+
+        if (targetProblem.PaidOnly)
+        {
+            throw new Exception("Target problem is paid only.");
+        }
+
+        if (targetProblem.Stat.QuestionTitleSlug is null)
+        {
+            throw new Exception("Failed to get problem title.");
+        }
+
+        var query = new Query(targetProblem.Stat.QuestionTitleSlug);
+        var response = await _httpClient.PostAsJsonAsync(
+            GraphQlUrl, query, _serializerOptions);
+        response.EnsureSuccessStatusCode();
+
+        var rawProblem = await JsonSerializer.DeserializeAsync<RawProblem>(
+                             await response.Content.ReadAsStreamAsync(), _serializerOptions)
+                         ?? throw new Exception("Failed to get raw problem.");
+
+        var returnType = rawProblem.Data.Question.MetaData.Replace("\"", "");
+
+        return new Problem
+        {
+            Title = targetProblem.Stat.QuestionTitle
+                    ?? throw new Exception("Failed to get question title"),
+            TitleSlug = targetProblem.Stat.QuestionTitleSlug
+                        ?? throw new Exception("Failed to get question title slug"),
+            Content = rawProblem.Data.Question.Content,
+            QuestionId = questionId,
+            ReturnType = returnType,
+            CodeDefinition = JsonSerializer.Deserialize<List<CodeDefinition>>(
+                                 rawProblem.Data.Question.CodeDefinition, _serializerOptions)
+                             ?? throw new Exception("Failed to get code definition.")
+        };
+    }
+
+
+}
+

LeetCodeSharp.Fetcher/LeetCodeSharp.Fetcher.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

LeetCodeSharp.Fetcher/Models/CodeDefinition.cs

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+using System.Text.Json.Serialization;
+
+namespace LeetCodeSharp.Fetcher.Models;
+
+internal class CodeDefinition
+{
+    public required string Value { get; set; }
+
+    public required string Text { get; set; }
+
+    [JsonPropertyName("defaultCode")]
+    public required string DefaultCode { get; set; }
+}

LeetCodeSharp.Fetcher/Models/Problem.cs

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+using System.Text;
+
+namespace LeetCodeSharp.Fetcher.Models;
+
+internal class Problem
+{
+    private const string Template = """
+                                    /**
+                                    * [__PROBLEM_ID__] __PROBLEM_TITLE__
+                                    */
+                                    __EXTRA_USE__
+                                    
+                                    namespace LeetCodeSharp.Problems
+                                    {
+
+                                        // Submission codes start here
+                                    
+                                        __PROBLEM_CODE__
+                                    
+                                        // Submission codes end here
+                                    }
+                                    """;
+
+    public required string Title { get; set; }
+
+    public required string TitleSlug { get; set; }
+
+    public required string Content { get; set; }
+
+    public required List<CodeDefinition> CodeDefinition { get; set; }
+
+    public required uint QuestionId { get; set; }
+
+    public required string ReturnType { get; set; }
+
+    public string GetFilename()
+    {
+        return $"p{QuestionId}_{TitleSlug.Replace('-', '_')}.cs";
+    }
+
+    public string GetFileContent()
+    {
+        var code = CodeDefinition.FirstOrDefault(c => c.Value == "csharp")
+            ?? throw new Exception("Target question has no C# version.");
+
+        string template;
+        if (code.DefaultCode.Contains("public class ListNode")
+            || code.DefaultCode.Contains("public class Point")
+            || code.DefaultCode.Contains("public class TreeNode")
+            || code.DefaultCode.Contains("public class Node"))
+        {
+            template = Template.Replace("__EXTRA_USE__", "using LeetCodeSharp.Utils;");
+        }
+        else
+        {
+            template = Template.Replace("__EXTRA_USE__", string.Empty);
+        }
+
+        return template.Replace("__PROBLEM_ID__", Title)
+            .Replace("__PROBLEM_TITLE__", QuestionId.ToString())
+            .Replace("__PROBLEM_CODE__", code.DefaultCode);
+    }
+
+    public override string ToString()
+    {
+        var builder = new StringBuilder();
+
+        builder.Append("Title:").Append(Title).Append("\r\n");
+        builder.Append("Title slug: ").Append(TitleSlug).Append("\r\n");
+        builder.Append("Code definitions: \r\n");
+        foreach (var definition in CodeDefinition)
+        {
+            builder.Append('\t').Append(definition.Value).Append("\r\n");
+        }
+        builder.Append("Return type: ").Append(ReturnType).Append("\r\n");
+
+        return builder.ToString();
+    }
+}

LeetCodeSharp.Fetcher/Models/Problems.cs

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+namespace LeetCodeSharp.Fetcher.Models;
+
+internal class Problems
+{
+    public required List<StatWithStatus> StatStatusPairs { get; set; }
+}

LeetCodeSharp.Fetcher/Models/Query.cs

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+using System.Text.Json.Serialization;
+
+namespace LeetCodeSharp.Fetcher.Models;
+
+internal class Query
+{
+    [JsonPropertyName("operationName")]
+    public string OperationName { get; init; }
+
+    public Dictionary<string, string> Variables { get; } = [];
+
+    [JsonPropertyName("query")]
+    public string QueryString { get; init; }
+
+    public Query(string title)
+    {
+        OperationName = "questionData";
+        Variables.Add("titleSlug", title);
+        QueryString = """
+                      query questionData($titleSlug: String!) {
+                          question(titleSlug: $titleSlug) {
+                              content
+                              stats
+                              codeDefinition
+                              sampleTestCase
+                              metaData
+                          }
+                      }
+                      """;
+    }
+}

LeetCodeSharp.Fetcher/Models/Question.cs

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+using System.Text.Json.Serialization;
+
+namespace LeetCodeSharp.Fetcher.Models;
+
+internal class Question
+{
+    public required string Content { get; set; }
+
+    public required string Stats { get; set; }
+
+    [JsonPropertyName("codeDefinition")]
+    public required string CodeDefinition { get; set; }
+
+    [JsonPropertyName("sampleTestCase")]
+    public required string SampleTestCase { get; set; }
+
+    [JsonPropertyName("metaData")]
+    public required string MetaData { get; set; }
+}
+
+internal class Data
+{
+    public required Question Question { get; set; }
+}
+
+internal class RawProblem
+{
+    public required Data Data { get; set; }
+}

LeetCodeSharp.Fetcher/Models/Stat.cs

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+using System.Text.Json.Serialization;
+
+namespace LeetCodeSharp.Fetcher.Models;
+
+internal class Stat
+{
+    public required uint QuestionId { get; set; }
+
+    [JsonPropertyName("question__article_slug")]
+    public string? QuestionArticleSlug { get; set; }
+
+    [JsonPropertyName("question__title")]
+    public string? QuestionTitle { get; set; }
+
+    [JsonPropertyName("question__title_slug")]
+    public string? QuestionTitleSlug { get; set; }
+
+    [JsonPropertyName("question__hide")]
+    public bool QuestionHide { get; set; }
+
+    public required uint TotalAcs { get; set; }
+    
+    public required uint TotalSubmitted { get; set; }
+
+    public required string FrontendQuestionId { get; set; }
+
+    public required bool IsNewQuestion { get; set; }
+}
+
+internal class StatWithStatus
+{
+    public required Stat Stat { get; set; }
+
+    public required bool PaidOnly { get; set; }
+}

LeetCodeSharp.Fetcher/Program.cs

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+using LeetCodeSharp.Fetcher;
+
+var directories = Directory.EnumerateDirectories(Environment.CurrentDirectory);
+
+if (!directories.Any(d => d.Contains("Problems")))
+{
+    Console.WriteLine("Please run in correct directory!");
+    return;
+}
+
+var problemDirectory = Path.Combine(Environment.CurrentDirectory, "Problems");
+var fetcher = new Fetcher();
+
+var problem = await fetcher.GetProblem(uint.Parse(args[0]));
+var problemFilename = Path.Combine(problemDirectory, problem.GetFilename());
+
+await using var writer = new StreamWriter(problemFilename);
+await writer.WriteAsync(problem.GetFileContent());

LeetCodeSharp.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.9.34607.119
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "LeetCodeSharp", "LeetCodeSharp\LeetCodeSharp.csproj", "{EB1DDDC1-A2FC-4AAB-A21A-59FAAFF656DD}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "LeetCodeSharp.Fetcher", "LeetCodeSharp.Fetcher\LeetCodeSharp.Fetcher.csproj", "{5D45BB2A-E512-4353-8746-6F0B79282C76}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{EB1DDDC1-A2FC-4AAB-A21A-59FAAFF656DD}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{EB1DDDC1-A2FC-4AAB-A21A-59FAAFF656DD}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{EB1DDDC1-A2FC-4AAB-A21A-59FAAFF656DD}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{EB1DDDC1-A2FC-4AAB-A21A-59FAAFF656DD}.Release|Any CPU.Build.0 = Release|Any CPU
+		{5D45BB2A-E512-4353-8746-6F0B79282C76}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{5D45BB2A-E512-4353-8746-6F0B79282C76}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{5D45BB2A-E512-4353-8746-6F0B79282C76}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{5D45BB2A-E512-4353-8746-6F0B79282C76}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {D28602CA-DA79-4D3C-A539-2FEB01BBEDA4}
+	EndGlobalSection
+EndGlobal

LeetCodeSharp.sln.DotSettings

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+<wpf:ResourceDictionary xml:space="preserve" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:ss="urn:shemas-jetbrains-com:settings-storage-xaml" xmlns:wpf="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=Leet/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>

LeetCodeSharp/LeetCodeSharp.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<TargetFramework>netstandard2.1</TargetFramework>
+		<ImplicitUsings>disable</ImplicitUsings>
+		<Nullable>disable</Nullable>
+	</PropertyGroup>
+
+	<ItemGroup>
+	  <Folder Include="Problems\" />
+	</ItemGroup>
+
+</Project>

LeetCodeSharp/Problems/p589_n_ary_tree_preorder_traversal.cs

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+/**
+* [N-ary Tree Preorder Traversal] 589
+*/
+
+
+using LeetCodeSharp.Utils;
+using System.Collections.Generic;
+
+namespace LeetCodeSharp.Problems
+{
+
+    // Submission codes start here
+
+    /*
+// Definition for a Node.
+public class Node {
+    public int val;
+    public IList<Node> children;
+
+    public Node() {}
+
+    public Node(int _val) {
+        val = _val;
+    }
+
+    public Node(int _val,IList<Node> _children) {
+        val = _val;
+        children = _children;
+    }
+}
+*/
+
+    public partial class Solution
+    {
+        public IList<int> Preorder(Node root)
+        {
+
+            var dfs = new Dfs();
+
+            dfs.Search(root);
+            return dfs.Result;
+        }
+
+        private class Dfs   
+        {
+            public IList<int> Result { get; } = new List<int>();
+
+            public void Search(Node node)
+            {
+                if (node == null) return;
+
+                Result.Add(node.val);
+
+                foreach (var child in node.children)
+                {
+                    Search(child);
+                }
+            }
+        }
+    }
+
+    // Submission codes end here
+}

LeetCodeSharp/Utils/ListNode.cs

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+namespace LeetCodeSharp.Utils
+{
+    public class ListNode
+    {
+        public int val;
+
+        public ListNode next;
+
+        public ListNode(int val = 0, ListNode next = null)
+        {
+            this.val = val;
+            this.next = next;
+        }
+    }
+}

LeetCodeSharp/Utils/Node.cs

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+using System.Collections.Generic;
+
+namespace LeetCodeSharp.Utils
+{
+    public class Node
+    {
+        public int val;
+        public IList<Node> children;
+
+        public Node() { }
+
+        public Node(int _val)
+        {
+            val = _val;
+        }
+
+        public Node(int _val, IList<Node> _children)
+        {
+            val = _val;
+            children = _children;
+        }
+    }
+}

LeetCodeSharp/Utils/Point.cs

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+namespace LeetCodeSharp.Utils
+{
+    public class Point
+    {
+        public int x;
+    
+        public int y;
+
+        public Point(int x, int y)
+        {
+            this.x  = x; 
+            this.y = y;
+        }
+    }
+}

LeetCodeSharp/Utils/TreeNode.cs

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+namespace LeetCodeSharp.Utils
+{
+    public class TreeNode
+    {
+        public int val;
+    
+        public TreeNode left;
+    
+        public TreeNode right;
+
+        public TreeNode(int val = 0, TreeNode left = null, TreeNode right = null)
+        {
+            this.val = val;
+            this.left = left;
+            this.right = right;
+        }
+    }
+}