commit 9ddcad2f0896a870c21dfb07014280cb36be5c64
Author: jackfiled <xcrenchangjun@outlook.com>
Date:   Thu Jun 12 22:23:50 2025 +0800

    init repo.

diff --git a/.clang-format b/.clang-format
new file mode 100644
index 0000000..f669e03
--- /dev/null
+++ b/.clang-format
@@ -0,0 +1,163 @@
+# public, protected, private 修饰符对齐
+# AccessModifierOffset: 2
+
+# 长函数调用时，参数对齐, 括号形式
+# someLongFunction(
+#     argument1, argument2
+# )
+#
+AlignAfterOpenBracket: BlockIndent
+AlignArrayOfStructures: None
+
+# 连续的赋值语句对齐
+AlignConsecutiveAssignments:
+  Enabled: true
+  AcrossEmptyLines: false
+  AcrossComments: false
+  AlignCompound: true
+  PadOperators: true
+
+#AlignConsecutiveBitFields: false
+AlignConsecutiveDeclarations: None
+AlignConsecutiveMacros: None
+AlignEscapedNewlines: Right
+
+# Align
+# x = aaaaaaaa +
+#     bbbbbbbb
+#
+#   when BreakBeforeBinaryOperators is set
+#
+# x = aaaaaaaa +
+#     bbbbbbbb
+#
+# AlignAfterOperator
+# x = aaaaaaaa
+#   + bbbbbbbb
+#AlignOperands: AlignAfterOperator
+
+AlignTrailingComments:
+  Kind: Always
+  OverEmptyLines: 2
+
+    # true:
+    # callFunction(
+    # a, b, c, d);
+    #
+    # false:
+    # callFunction(a,
+    # b,
+  # c,
+  # d);
+AllowAllArgumentsOnNextLine: false
+AllowAllConstructorInitializersOnNextLine: false
+AllowAllParametersOfDeclarationOnNextLine: false
+AllowShortBlocksOnASingleLine: Never
+AllowShortCaseLabelsOnASingleLine: true
+#AllowShortEnumsOnASingleLine: true
+AllowShortFunctionsOnASingleLine: Inline
+AllowShortIfStatementsOnASingleLine: Never
+AllowShortLambdasOnASingleLine: Empty
+AllowShortLoopsOnASingleLine: false
+
+AlwaysBreakAfterReturnType: None
+AlwaysBreakBeforeMultilineStrings: false
+
+# 在template声明时，是否换行
+# template <typename T>
+# T foo() {
+# }
+# template <typename T>
+# T foo(int aaaaaaaaaaaaaaaaaaaaa,
+#       int bbbbbbbbbbbbbbbbbbbbb) {
+# }
+AlwaysBreakTemplateDeclarations: Yes
+
+BinPackArguments: false
+BinPackParameters: false
+#BitFieldColonSpacing: Both
+BreakBeforeBraces: "Allman"
+
+# true:
+# veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongDescription
+#     ? firstValue
+#     : SecondValueVeryVeryVeryVeryLong;
+#
+# false:
+# veryVeryVeryVeryVeryVeryVeryVeryVeryVeryVeryLongDescription ?
+#     firstValue :
+#     SecondValueVeryVeryVeryVeryLong;
+BreakBeforeTernaryOperators: true
+BreakConstructorInitializers: BeforeComma
+BreakStringLiterals: false
+
+ColumnLimit: 0 # 0: no limit
+CompactNamespaces: false
+ConstructorInitializerIndentWidth: 4
+Cpp11BracedListStyle: true
+
+
+
+FixNamespaceComments: true # 加上丢失的namespace注释
+IncludeBlocks: Preserve
+#IndentCaseBlocks: false
+IndentCaseLabels: true
+IndentGotoLabels: false
+
+# #if FOO
+#   #if BAR
+#     #include <foo>
+#   #endif
+# #endif
+IndentPPDirectives: BeforeHash
+# IndentAccessModifiers: true
+IndentWidth: 4
+KeepEmptyLinesAtTheStartOfBlocks: false
+MaxEmptyLinesToKeep: 3
+NamespaceIndentation: None
+
+# Left:
+# int* a;
+# Right:
+# int *a;
+# Middle:
+# int * a;
+PointerAlignment: Right
+
+# QualifierOrder
+
+ReferenceAlignment: Right
+
+# 按照列数限制, 将注释进行换行
+ReflowComments: false
+
+SortIncludes: CaseSensitive
+SortUsingDeclarations: true
+
+SpaceAfterCStyleCast: false
+SpaceAfterLogicalNot: false
+SpaceAfterTemplateKeyword: false
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeCpp11BracedList: false
+SpaceBeforeCaseColon: false
+SpaceBeforeCtorInitializerColon: false
+SpaceBeforeInheritanceColon: false
+SpaceBeforeParens: ControlStatements
+SpaceBeforeRangeBasedForLoopColon: true
+SpaceBeforeSquareBrackets: false
+SpaceInEmptyBlock: false
+SpaceInEmptyParentheses: false
+SpacesBeforeTrailingComments: 4
+SpacesInAngles: Leave
+SpacesInCStyleCastParentheses: false
+SpacesInConditionalStatement: false
+SpacesInContainerLiterals: false
+SpacesInParentheses: false
+SpacesInSquareBrackets: false
+
+# Constructor
+ConstructorInitializerAllOnOneLineOrOnePerLine: true
+
+Standard: c++20
+TabWidth: 4
+UseTab: Never
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..dc9c276
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+.idea/
+build/
+cmake-build-*/
\ No newline at end of file
diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..e2f9fe9
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,14 @@
+cmake_minimum_required(VERSION 3.20)
+project(leetcode-cpp)
+
+set(CMAKE_CXX_STANDARD 20)
+include_directories(include)
+
+find_package(CURL REQUIRED)
+find_package(nlohmann_json REQUIRED)
+
+add_executable(leetcode-fetcher main.cpp
+        src/fetcher.cpp)
+
+target_link_libraries(leetcode-fetcher PRIVATE CURL::libcurl)
+target_link_libraries(leetcode-fetcher PRIVATE nlohmann_json::nlohmann_json)
diff --git a/include/fetcher.h b/include/fetcher.h
new file mode 100644
index 0000000..d6d42b9
--- /dev/null
+++ b/include/fetcher.h
@@ -0,0 +1,126 @@
+//
+// Created by ricardo on 12/06/25.
+//
+
+#ifndef FETCHER_H
+#define FETCHER_H
+#include <iostream>
+#include <memory>
+#include <curl/curl.h>
+#include <nlohmann/json.hpp>
+
+struct CurlDeleter
+{
+    void operator()(CURL *curl) const
+    {
+        if (curl != nullptr)
+        {
+            curl_easy_cleanup(curl);
+        }
+    }
+};
+
+struct LeetCodeProblem
+{
+    LeetCodeProblem(bool paidOnly,
+                    std::string frontendQuestionId,
+                    int questionId,
+                    std::string questionTitle,
+                    std::string questionTitleSlug)
+        : paidOnly(paidOnly)
+        , frontendQuestionId(std::move(frontendQuestionId))
+        , questionId(questionId)
+        , questionTitle(std::move(questionTitle))
+        , questionTitleSlug(std::move(questionTitleSlug))
+    {
+    }
+
+    bool paidOnly;
+    std::string frontendQuestionId;
+    int questionId;
+    std::string questionTitle;
+    std::string questionTitleSlug;
+};
+
+struct CodeDefinition
+{
+    std::string value;
+    std::string text;
+    std::string defaultCode;
+
+    CodeDefinition(std::string value, std::string text, std::string defaultCode)
+        : value(std::move(value))
+        , text(std::move(text))
+        , defaultCode(std::move(defaultCode))
+    {
+    }
+};
+
+struct ProblemContent
+{
+    std::string title;
+    std::string title_slug;
+    std::string content;
+    std::vector<CodeDefinition> codeDefinitions;
+    int questionId;
+
+    ProblemContent(std::string title,
+                   std::string title_slug,
+                   std::string content,
+                   std::vector<CodeDefinition> codeDefinitions,
+                   int questionId)
+        : title(std::move(title))
+        , title_slug(std::move(title_slug))
+        , content(std::move(content))
+        , codeDefinitions(std::move(codeDefinitions))
+        , questionId(questionId)
+    {
+    }
+
+    std::string formatTemplate(const std::string &templateContent) const;
+};
+
+struct Fetcher
+{
+    Fetcher()
+    {
+        // Initialize the cURL global environment.
+        curl_global_init(CURL_GLOBAL_ALL);
+        client = std::unique_ptr<CURL, CurlDeleter>(curl_easy_init());
+    }
+
+    ~Fetcher()
+    {
+        curl_global_cleanup();
+    }
+
+    void fetchProblem(const std::string &idString) const;
+
+private:
+    std::unique_ptr<CURL, CurlDeleter> client;
+
+    std::string kProblemsUrl = "https://leetcode.cn/api/problems/algorithms/";
+    std::string kGraphQlUrl = "https://leetcode.cn/graphql";
+
+    [[nodiscard]] std::vector<LeetCodeProblem> getProblems() const;
+
+    /// The callback function used by curl to write the http response content into a string.
+    static size_t httpWriteCallback(void *contents, const size_t size, size_t bufferLength, void *userData)
+    {
+        auto string = static_cast<std::string *>(userData);
+        auto body = static_cast<char *>(contents);
+        string->append(body, size * bufferLength);
+
+        return size * bufferLength;
+    }
+
+    static nlohmann::json formatQueryJson(const std::string &title);
+
+    static std::unique_ptr<ProblemContent> extractContentFromJson(
+        const nlohmann::json &json,
+        const LeetCodeProblem &problem);
+
+    static std::string readTemplateFile();
+};
+
+#endif //FETCHER_H
\ No newline at end of file
diff --git a/main.cpp b/main.cpp
new file mode 100644
index 0000000..45a512f
--- /dev/null
+++ b/main.cpp
@@ -0,0 +1,16 @@
+#include "fetcher.h"
+
+int main(int argc, char **argv)
+{
+    Fetcher fetcher;
+
+    if (argc != 2)
+    {
+        std::cout << "The fetcher expect the program id.";
+        return -1;
+    }
+
+    fetcher.fetchProblem(argv[1]);
+
+    return 0;
+}
\ No newline at end of file
diff --git a/src/fetcher.cpp b/src/fetcher.cpp
new file mode 100644
index 0000000..5069883
--- /dev/null
+++ b/src/fetcher.cpp
@@ -0,0 +1,228 @@
+//
+// Created by ricardo on 12/06/25.
+//
+#include <fstream>
+#include "fetcher.h"
+
+std::vector<LeetCodeProblem> Fetcher::getProblems() const
+{
+    std::string body;
+
+    curl_easy_setopt(client.get(), CURLOPT_URL, kProblemsUrl.c_str());
+    curl_easy_setopt(client.get(), CURLOPT_WRITEFUNCTION, Fetcher::httpWriteCallback);
+    curl_easy_setopt(client.get(), CURLOPT_WRITEDATA, &body);
+
+    const CURLcode code = curl_easy_perform(client.get());
+
+    if (code != CURLE_OK)
+    {
+        std::cout << "Failed to fetch problems." << std::endl;
+        return {};
+    }
+
+    std::vector<LeetCodeProblem> problems;
+
+    try
+    {
+        nlohmann::json jsonResponse = nlohmann::json::parse(body);
+
+        for (const auto &item : jsonResponse["stat_status_pairs"])
+        {
+            bool paidOnly = item["paid_only"];
+
+            const auto &stat_item = item["stat"];
+
+            std::string frontendQuestionId = stat_item["frontend_question_id"];
+            int questionId = stat_item["question_id"];
+            std::string questionTitle = stat_item["question__title"];
+            std::string questionTitleSlug = stat_item["question__title_slug"];
+
+            problems.emplace_back(paidOnly, frontendQuestionId, questionId, questionTitle, questionTitleSlug);
+        }
+    }
+    catch (const nlohmann::json::parse_error &e)
+    {
+        std::cout << "JSON parse error: " << e.what() << std::endl;
+        std::cout << "Raw response: " << body << std::endl;
+    }
+
+    return problems;
+}
+
+std::string replaceString(const std::string &original,
+                          const std::string_view old_sub,
+                          const std::string_view new_sub)
+{
+    if (old_sub.empty())
+        return original; // 防止空字符串导致死循环
+
+    std::string result;
+    size_t pos = 0;
+    size_t old_len = old_sub.size();
+    size_t new_len = new_sub.size();
+
+    // 预计算总长度以减少内存分配
+    size_t total_length = original.size();
+    size_t count = 0;
+    size_t start = 0;
+
+    while ((pos = original.find(old_sub, start)) != std::string::npos)
+    {
+        total_length += (new_len - old_len); // 更新总长度
+        count++;
+        start = pos + old_len; // 下一次查找起始位置
+    }
+
+    result.reserve(total_length); // 预分配内存
+
+    start = 0;
+    while ((pos = original.find(old_sub, start)) != std::string::npos)
+    {
+        // 添加旧子串之前的部分
+        result.append(original.data() + start, pos - start);
+        // 添加新子串
+        result.append(new_sub.data(), new_sub.size());
+        // 更新起始位置
+        start = pos + old_len;
+    }
+
+    // 添加剩余部分
+    result.append(original.data() + start, original.size() - start);
+
+    return result;
+}
+
+std::string ProblemContent::formatTemplate(const std::string &templateContent) const
+{
+    const auto it = std::ranges::find_if(codeDefinitions,
+                                         [](const CodeDefinition &definition)
+                                         {
+                                             return definition.value == "cpp";
+                                         });
+
+    if (it == codeDefinitions.end())
+    {
+        throw std::runtime_error("The target problem has no C++ template.");
+    }
+
+    std::string result = replaceString(templateContent, "__PROBLEM_ID__", std::to_string(questionId));
+    result = replaceString(result, "__PROBLEM_TITLE__", title);
+    result = replaceString(result, "__PROBLEM_DEFAULT_CODE__", it->defaultCode);
+
+    return result;
+}
+
+void Fetcher::fetchProblem(const std::string &idString) const
+{
+    std::vector<LeetCodeProblem> problems = getProblems();
+
+    const auto it = std::ranges::find_if(problems,
+                                         [idString](const LeetCodeProblem &problem)
+                                         {
+                                             return problem.frontendQuestionId == idString;
+                                         });
+
+    if (it == problems.end())
+    {
+        throw std::runtime_error("The target problem does not exist.");
+    }
+
+    curl_easy_setopt(client.get(), CURLOPT_URL, kGraphQlUrl.c_str());
+    curl_easy_setopt(client.get(), CURLOPT_POST, 1L);
+
+    curl_slist *headers = nullptr;
+    headers = curl_slist_append(headers, "Content-Type: application/json");
+
+    curl_easy_setopt(client.get(), CURLOPT_HTTPHEADER, headers);
+
+    std::string requestBody = formatQueryJson(it->questionTitleSlug).dump();
+
+    curl_easy_setopt(client.get(), CURLOPT_POSTFIELDS, requestBody.c_str());
+    curl_easy_setopt(client.get(), CURLOPT_POSTFIELDSIZE, requestBody.size());
+
+    std::string responseBody;
+
+    curl_easy_setopt(client.get(), CURLOPT_WRITEFUNCTION, Fetcher::httpWriteCallback);
+    curl_easy_setopt(client.get(), CURLOPT_WRITEDATA, &responseBody);
+
+    CURLcode code = curl_easy_perform(client.get());
+
+    if (code != CURLE_OK)
+    {
+        throw std::runtime_error("Failed to fetch problem.");
+    }
+
+    const nlohmann::json jsonResponse = nlohmann::json::parse(responseBody);
+    const std::unique_ptr<ProblemContent> problemContent = extractContentFromJson(jsonResponse, *it);
+
+    std::string templateFile = readTemplateFile();
+
+    std::cout << problemContent->formatTemplate(templateFile) << std::endl;
+}
+
+nlohmann::json Fetcher::formatQueryJson(const std::string &title)
+{
+    nlohmann::json result;
+
+    result["operationName"] = "questionData";
+    result["query"] = R"(query questionData($titleSlug: String!) {
+    question(titleSlug: $titleSlug) {
+        content
+        stats
+        codeDefinition
+        sampleTestCase
+    }
+})";
+
+    nlohmann::json variables;
+    variables["titleSlug"] = title;
+    result["variables"] = variables;
+
+    return result;
+}
+
+std::unique_ptr<ProblemContent> Fetcher::extractContentFromJson(const nlohmann::json &json, const LeetCodeProblem &problem)
+{
+    const auto questionJson = json["data"]["question"];
+    std::string content = questionJson["content"];
+
+    std::vector<CodeDefinition> codeDefinitions;
+    const std::string codeDefinitionString = questionJson["codeDefinition"];
+
+    for (nlohmann::json codeDefinitionJson = nlohmann::json::parse(codeDefinitionString);
+         const auto &codeDefinitionItem : codeDefinitionJson)
+    {
+        std::string value = codeDefinitionItem["value"];
+        std::string text = codeDefinitionItem["text"];
+        std::string defaultCode = codeDefinitionItem["defaultCode"];
+
+        codeDefinitions.emplace_back(value, text, defaultCode);
+    }
+
+    return std::make_unique<ProblemContent>(
+        problem.questionTitle,
+        problem.questionTitleSlug,
+        content,
+        codeDefinitions,
+        std::stoi(problem.frontendQuestionId));
+}
+
+std::string Fetcher::readTemplateFile()
+{
+    std::ifstream file;
+    file.open("src/template.cpp");
+
+    std::stringstream buffer;
+    if (file.is_open())
+    {
+        buffer << file.rdbuf();
+    }
+    else
+    {
+        throw std::runtime_error("Failed to read template file.");
+    }
+
+    file.close();
+
+    return buffer.str();
+}
\ No newline at end of file
diff --git a/src/template.cpp b/src/template.cpp
new file mode 100644
index 0000000..506658a
--- /dev/null
+++ b/src/template.cpp
@@ -0,0 +1,9 @@
+/**
+* [__PROBLEM_ID__] __PROBLEM_TITLE__
+ */
+
+// submission codes start here
+
+__PROBLEM_DEFAULT_CODE__
+
+// submission codes end