diff --git a/ElementaryQuestionStrategy.java b/ElementaryQuestionStrategy.java
new file mode 100644
index 0000000..120e106
--- /dev/null
+++ b/ElementaryQuestionStrategy.java
@@ -0,0 +1,151 @@
+import java.util.Random;
+
+public class ElementaryQuestionStrategy implements QuestionStrategy {
+    private final Random random = new Random();
+    private final String[] operators = {"+", "-", "*", "/"};
+
+    @Override
+    public String generateQuestion() {
+        int operandsCount = random.nextInt(4) + 2; // 操作数 2~5
+        StringBuilder sb = new StringBuilder();
+
+        // 生成运算符序列
+        String[] chosenOps = generateOperators(operandsCount);
+
+        // 随机决定括号
+        int[] parentheses = decideParentheses(operandsCount, chosenOps);
+
+        // 拼接表达式
+        buildExpression(sb, operandsCount, chosenOps, parentheses);
+
+        return sb.toString();
+    }
+
+    /**
+     * 生成运算符序列
+     * 根据操作数数量，随机生成对应数量的运算符数组
+     * 
+     * @param operandsCount 操作数数量
+     * @return 随机生成的运算符数组，长度为操作数数量-1
+     */
+    private String[] generateOperators(int operandsCount) {
+        String[] chosenOps = new String[operandsCount - 1];
+        for (int i = 0; i < operandsCount - 1; i++) {
+            chosenOps[i] = operators[random.nextInt(operators.length)];
+        }
+        return chosenOps;
+    }
+
+    /**
+     * 决定是否需要括号，并返回括号的起始和结束位置
+     * 对于3个及以上操作数，随机决定是否添加括号，并检查括号是否有效
+     * 
+     * @param operandsCount 操作数数量
+     * @param chosenOps 运算符数组
+     * @return 包含开括号和闭括号位置的数组，格式为[openParenIndex, closeParenIndex]，-1表示不添加括号
+     */
+    private int[] decideParentheses(int operandsCount, String[] chosenOps) {
+        int openParenIndex = -1;
+        int closeParenIndex = -1;
+
+        if (operandsCount > 2 && random.nextBoolean()) {
+            openParenIndex = random.nextInt(operandsCount - 1);
+            closeParenIndex = random.nextInt(operandsCount - openParenIndex - 1) + openParenIndex + 1;
+
+            // 如果括号包裹整个表达式，则不需要括号
+            if (openParenIndex == 0 && closeParenIndex == operandsCount - 1) {
+                openParenIndex = -1;
+                closeParenIndex = -1;
+            } else {
+                // 检查括号内的运算符优先级是否相同，如果相同则不需要括号
+                boolean samePrecedence = checkPrecedenceEquality(chosenOps, openParenIndex, closeParenIndex);
+                if (samePrecedence) {
+                    openParenIndex = -1;
+                    closeParenIndex = -1;
+                }
+            }
+        }
+        return new int[]{openParenIndex, closeParenIndex};
+    }
+
+    /**
+     * 判断括号内的运算符优先级是否相同
+     * 用于决定是否需要添加括号（如果优先级都相同，则括号是冗余的）
+     * 
+     * @param chosenOps 运算符数组
+     * @param openParenIndex 开括号位置
+     * @param closeParenIndex 闭括号位置
+     * @return 如果括号内所有运算符优先级相同则返回true，否则返回false
+     */
+    private boolean checkPrecedenceEquality(String[] chosenOps, int openParenIndex, int closeParenIndex) {
+        int precedence = getPrecedence(chosenOps[openParenIndex]);
+        for (int i = openParenIndex; i < closeParenIndex; i++) {
+            if (getPrecedence(chosenOps[i]) != precedence) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /**
+     * 构建数学表达式
+     * 根据操作数、运算符和括号位置，拼接完整的数学表达式
+     * 
+     * @param sb StringBuilder对象，用于构建表达式
+     * @param operandsCount 操作数数量
+     * @param chosenOps 运算符数组
+     * @param parentheses 括号位置数组，格式为[openParenIndex, closeParenIndex]
+     */
+    private void buildExpression(StringBuilder sb, int operandsCount, String[] chosenOps, int[] parentheses) {
+        int prevNum = random.nextInt(100) + 1;
+        int openParenIndex = parentheses[0];
+        int closeParenIndex = parentheses[1];
+
+        // 处理第一个操作数可能的开括号
+        if (openParenIndex == 0) sb.append("(");
+        sb.append(prevNum);
+        
+        // 处理最后一个操作数可能的闭括号
+        if (closeParenIndex == operandsCount - 1) sb.append(")");
+
+        // 构建剩余的操作数和运算符
+        for (int i = 1; i < operandsCount; i++) {
+            String op = chosenOps[i - 1];
+            sb.append(" ").append(op).append(" ");
+
+            // 根据运算符生成下一个操作数
+            int num = generateOperand(op, prevNum);
+
+            // 添加括号（如果需要）
+            if (i == openParenIndex) sb.append("(");
+            sb.append(num);
+            if (i == closeParenIndex) sb.append(")");
+
+            prevNum = num; // 更新上一个数字，供下一轮计算使用
+        }
+    }
+
+    /**
+     * 生成每个操作数
+     * 确保生成的操作数符合题目要求，特别是减法不会导致负数结果
+     * 
+     * @param op 当前运算符
+     * @param prevNum 前一个操作数的值
+     * @return 生成的操作数
+     */
+    private int generateOperand(String op, int prevNum) {
+        int num = random.nextInt(100) + 1; // 默认生成1-100之间的随机数
+
+        // 如果是减法运算符，确保不会出现负数结果
+        if (op.equals("-") && num > prevNum) {
+            num = random.nextInt(prevNum) + 1; // 保证 num <= prevNum，避免负数结果
+        }
+        return num;
+    }
+
+    private int getPrecedence(String op) {
+        if (op.equals("+") || op.equals("-")) return 1;
+        if (op.equals("*") || op.equals("/")) return 2;
+        return 0;
+    }
+}
diff --git a/FileUtils.java b/FileUtils.java
new file mode 100644
index 0000000..a24ab81
--- /dev/null
+++ b/FileUtils.java
@@ -0,0 +1,64 @@
+import java.io.*;
+import java.text.SimpleDateFormat;
+import java.util.*;
+
+/**
+ * 文件工具类：生成文件名、保存题目、读取已有题目
+ */
+public class FileUtils {
+
+    // 生成文件名
+    public static String generateFileName() {
+        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss");
+        return sdf.format(new Date()) + ".txt";
+    }
+
+    // 保存题目到用户文件夹
+    public static void saveQuestionsToFile(String userId, String fileName, List<MathQuestion> questions) {
+        File userFolder = new File(userId);
+        if (!userFolder.exists()) {
+            userFolder.mkdirs();
+        }
+
+        File file = new File(userFolder, fileName);
+        try (BufferedWriter writer = new BufferedWriter(new FileWriter(file))) {
+            for (MathQuestion question : questions) {
+                writer.write("题号 " + question.getQuestionNumber() + ": " + question.getQuestionText());
+                writer.newLine();
+                writer.newLine();
+            }
+            writer.flush();
+        } catch (IOException e) {
+            throw new RuntimeException("写文件失败: " + file.getAbsolutePath(), e);
+        }
+    }
+
+    // 读取用户文件夹下所有 txt 文件中已存在的题目
+    public static Set<String> loadExistingQuestions(String userId) {
+        Set<String> existingQuestions = new HashSet<>();
+        File userFolder = new File(userId);
+        if (!userFolder.exists() || !userFolder.isDirectory()) return existingQuestions;
+
+        File[] files = userFolder.listFiles((dir, name) -> name != null && name.endsWith(".txt"));
+        if (files == null) return existingQuestions;
+
+        for (File f : files) {
+            try (BufferedReader reader = new BufferedReader(new FileReader(f))) {
+                String line;
+                while ((line = reader.readLine()) != null) {
+                    line = line.trim();
+                    if (line.isEmpty()) continue;
+                    if (line.startsWith("题号")) {
+                        int idx = line.indexOf(":");
+                        if (idx != -1 && idx + 1 < line.length()) {
+                            existingQuestions.add(line.substring(idx + 1).trim());
+                        }
+                    }
+                }
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+        return existingQuestions;
+    }
+}
diff --git a/HighSchoolQuestionStrategy.java b/HighSchoolQuestionStrategy.java
new file mode 100644
index 0000000..85812b9
--- /dev/null
+++ b/HighSchoolQuestionStrategy.java
@@ -0,0 +1,42 @@
+import java.util.Random;
+
+public class HighSchoolQuestionStrategy implements QuestionStrategy {
+    private final Random random = new Random();
+    private final String[] basicOps = {"+", "-", "*", "/"};
+    private final String[] trigFuncs = {"sin", "cos", "tan"};
+
+    @Override
+    public String generateQuestion() {
+        // 随机操作数个数 2-5
+        int operandsCount = random.nextInt(4) + 2;
+        StringBuilder sb = new StringBuilder();
+        boolean hasTrig = false;
+
+        for (int i = 0; i < operandsCount; i++) {
+            int num = random.nextInt(100) + 1;
+
+            // 每个操作数有概率加三角函数
+            if (random.nextBoolean()) {
+                String func = trigFuncs[random.nextInt(trigFuncs.length)];
+                sb.append(func).append("(").append(num).append(")");
+                hasTrig = true;
+            } else {
+                sb.append(num);
+            }
+
+            if (i != operandsCount - 1) {
+                String op = basicOps[random.nextInt(basicOps.length)];
+                sb.append(" ").append(op).append(" ");
+            }
+        }
+
+        // 确保至少一个三角函数
+        if (!hasTrig) {
+            String func = trigFuncs[random.nextInt(trigFuncs.length)];
+            int num = random.nextInt(100) + 1;
+            return func + "(" + num + ") + " + sb.toString();
+        }
+
+        return sb.toString();
+    }
+}
diff --git a/Main.java b/Main.java
new file mode 100644
index 0000000..3a5deeb
--- /dev/null
+++ b/Main.java
@@ -0,0 +1,100 @@
+import java.io.IOException;
+import java.util.Scanner;
+
+/**
+ * 程序入口类，负责处理登录和题目生成。
+ */
+public class Main {
+    public static void main(String[] args) throws IOException {
+        Scanner scanner = new Scanner(System.in);
+        User currentUser = null;
+
+        // 登录流程
+        while (true) {
+            while (currentUser == null) {
+                System.out.print("请输入用户名和密码，用空格分隔：");
+                String username = scanner.next();
+                String password = scanner.next();
+
+                currentUser = User.login(username, password);
+
+                if (currentUser == null) {
+                    System.out.println("请输入正确的用户名、密码");
+                } else {
+                    clearScreen(); //登录成功清屏
+                    System.out.println("当前选择为 " + currentUser.getRole() + " 出题");
+                }
+            }
+
+            // 每次登录后初始化当前出题类型（账号默认类型）
+            String currentRole = currentUser.getRole();
+
+            // 题目生成流程
+            while (true) {
+                System.out.println("准备生成 " + currentRole
+                        + " 数学题目，请输入生成题目数量（输入-1将退出当前用户，重新登录）：");
+
+                String input = scanner.next();
+
+                // 退出登录
+                if (input.equals("-1")) {
+                    currentUser = null;
+                    clearScreen();
+                    System.out.println("已退出当前用户，重新登录...");
+                    break;
+                }
+
+                // 检测切换命令
+                if (input.startsWith("切换为")) {
+                    String newRole = input.substring(3).trim();
+                    if (!newRole.equals("小学") && !newRole.equals("初中") && !newRole.equals("高中")) {
+                        System.out.println("请输入小学、初中和高中三个选项中的一个"+"(当前类型为"+currentRole+")");
+                        continue;
+                    }
+                    currentRole = newRole;
+                    clearScreen();
+                    System.out.println("系统提示：准备生成 " + currentRole + " 数学题目，请输入生成题目数量");
+                    continue;
+                }
+
+                // 输入题目数量
+                int questionCount;
+                try {
+                    questionCount = Integer.parseInt(input);
+                } catch (NumberFormatException e) {
+                    System.out.println("请输入有效的数字或使用“切换为小学/初中/高中”命令"+"(当前类型为"+currentRole+")");
+                    continue;
+                }
+
+                if (questionCount < 10 || questionCount > 30) {
+                    System.out.println("请输入有效的题目数量 (10-30) 或 -1 退出");
+                    continue;
+                }
+
+                clearScreen();
+
+                // 把 currentRole 传给 QuestionGenerator
+                QuestionGenerator generator = new QuestionGenerator(currentUser, currentRole);
+                generator.generateQuestions(questionCount);
+                System.out.println("题目已生成并保存！\n");
+            }
+        }
+    }
+
+    /**
+     * 清屏方法
+     */
+    public static void clearScreen() {
+        try {
+            if (System.getProperty("os.name").contains("Windows")) {
+                new ProcessBuilder("cmd", "/c", "cls").inheritIO().start().waitFor();
+            } else {
+                new ProcessBuilder("clear").inheritIO().start().waitFor();
+            }
+        } catch (Exception e) {
+            for (int i = 0; i < 50; i++) {
+                System.out.println();
+            }
+        }
+    }
+}
diff --git a/MathQuestion.java b/MathQuestion.java
new file mode 100644
index 0000000..c727b28
--- /dev/null
+++ b/MathQuestion.java
@@ -0,0 +1,21 @@
+/**
+ * 数学题目类，表示每一道数学题。
+ */
+public class MathQuestion {
+    private int questionNumber;
+    private String questionText;
+
+    // 构造方法
+    public MathQuestion(int questionNumber, String questionText) {
+        this.questionNumber = questionNumber;
+        this.questionText = questionText;
+    }
+
+    public int getQuestionNumber() {
+        return questionNumber;
+    }
+
+    public String getQuestionText() {
+        return questionText;
+    }
+}
diff --git a/MiddleSchoolQuestionStrategy.java b/MiddleSchoolQuestionStrategy.java
new file mode 100644
index 0000000..aa4c595
--- /dev/null
+++ b/MiddleSchoolQuestionStrategy.java
@@ -0,0 +1,47 @@
+import java.util.Random;
+
+public class MiddleSchoolQuestionStrategy implements QuestionStrategy {
+    private final Random random = new Random();
+    private final String[] basicOps = {"+", "-", "*", "/"}; // 基本运算符
+
+    @Override
+    public String generateQuestion() {
+        // 随机操作数个数 2-5
+        int operandsCount = random.nextInt(4) + 2;
+        StringBuilder sb = new StringBuilder();
+        boolean hasSquareOrRoot = false;
+
+        // 生成运算符和操作数
+        for (int i = 0; i < operandsCount; i++) {
+            int num = random.nextInt(100) + 1; // 生成1-100之间的数字
+
+            // 每个操作数有概率平方或开根号
+            if (random.nextBoolean()) {
+                if (random.nextBoolean()) {
+                    sb.append("(").append(num).append(")^2");
+                    hasSquareOrRoot = true; // 标记是否已经使用了平方或根号
+                } else {
+                    // 确保根号下的数为正
+                    int rootNumber = random.nextInt(100) + 1; // 始终生成正整数
+                    sb.append("√(").append(rootNumber).append(")");
+                    hasSquareOrRoot = true; // 标记是否已经使用了平方或根号
+                }
+            } else {
+                sb.append(num); // 普通数字
+            }
+
+            // 添加运算符（除最后一个操作数外）
+            if (i != operandsCount - 1) {
+                String op = basicOps[random.nextInt(basicOps.length)];
+                sb.append(" ").append(op).append(" ");
+            }
+        }
+        // 如果没有平方或根号，强制添加一个
+        if (!hasSquareOrRoot) {
+            // 确保根号下的数为正
+            int rootNumber = random.nextInt(100) + 1; // 始终生成正整数
+            sb.append(" + √(").append(rootNumber).append(")");
+        }
+        return sb.toString();
+    }
+}
diff --git a/QuestionGenerator.java b/QuestionGenerator.java
new file mode 100644
index 0000000..bd56c29
--- /dev/null
+++ b/QuestionGenerator.java
@@ -0,0 +1,51 @@
+import java.io.IOException;
+import java.util.*;
+
+/**
+ * 题目生成器类
+ */
+public class QuestionGenerator {
+    private User user;
+    private String role;
+
+    public QuestionGenerator(User user, String role) {
+        this.user = user;
+        this.role = role;
+    }
+
+    public void generateQuestions(int questionCount) throws IOException {
+        // 获取策略
+        QuestionStrategy strategy = QuestionStrategyFactory.getStrategy(role);
+
+        // 读出该用户所有历史题目
+        Set<String> existingQuestions = FileUtils.loadExistingQuestions(user.getUsername());
+        Set<String> newQuestionsSet = new HashSet<>();
+        List<MathQuestion> questions = new ArrayList<>();
+
+        System.out.println("以下为生成的题目列表:\n");
+
+        int i = 1;
+        int tryCount = 0;
+        while (questions.size() < questionCount) {
+            String questionText = strategy.generateQuestion();
+            tryCount++;
+            if (existingQuestions.contains(questionText) || newQuestionsSet.contains(questionText)) {
+                // 如果题库太小可能死循环，这里设置最大尝试次数
+                if (tryCount > questionCount * 100) {
+                    System.out.println("题库不足，无法生成足够不重复的题目");
+                    break;
+                }
+                continue;
+            }
+
+            newQuestionsSet.add(questionText);
+            MathQuestion question = new MathQuestion(i, questionText);
+            questions.add(question);
+            System.out.println("题号 " + i + "：" + questionText + "\n");
+            i++;
+        }
+
+        String fileName = FileUtils.generateFileName();
+        FileUtils.saveQuestionsToFile(user.getUsername(), fileName, questions);
+    }
+}
diff --git a/QuestionRepository.java b/QuestionRepository.java
new file mode 100644
index 0000000..d4fbc17
--- /dev/null
+++ b/QuestionRepository.java
@@ -0,0 +1,26 @@
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * 题目仓库类，负责管理已生成的题目，避免重复。
+ */
+public class QuestionRepository {
+    private Set<String> generatedQuestions = new HashSet<>();
+
+    /**
+     * 检查题目是否重复
+     * @param question 题目
+     * @return 是否重复
+     */
+    public boolean isDuplicate(String question) {
+        return generatedQuestions.contains(question);
+    }
+
+    /**
+     * 将题目添加到仓库
+     * @param question 题目
+     */
+    public void addQuestion(String question) {
+        generatedQuestions.add(question);
+    }
+}
diff --git a/QuestionStrategy.java b/QuestionStrategy.java
new file mode 100644
index 0000000..079889b
--- /dev/null
+++ b/QuestionStrategy.java
@@ -0,0 +1,6 @@
+/**
+ * 出题策略接口
+ */
+public interface QuestionStrategy {
+    String generateQuestion();
+}
diff --git a/QuestionStrategyFactory.java b/QuestionStrategyFactory.java
new file mode 100644
index 0000000..e565ff5
--- /dev/null
+++ b/QuestionStrategyFactory.java
@@ -0,0 +1,17 @@
+/**
+ * 出题策略工厂类，根据role返回对应策略
+ */
+public class QuestionStrategyFactory {
+    public static QuestionStrategy getStrategy(String role) {
+        switch (role) {
+            case "小学":
+                return new ElementaryQuestionStrategy();
+            case "初中":
+                return new MiddleSchoolQuestionStrategy();
+            case "高中":
+                return new HighSchoolQuestionStrategy();
+            default:
+                throw new IllegalArgumentException("未知的角色: " + role);
+        }
+    }
+}
diff --git a/User.java b/User.java
new file mode 100644
index 0000000..56f2691
--- /dev/null
+++ b/User.java
@@ -0,0 +1,52 @@
+/**
+ * 用户类，包含登录验证和角色管理。
+ */
+public class User {
+    private String username;
+    private String password;
+    private String role;
+
+    // 构造方法
+    public User(String username, String password, String role) {
+        this.username = username;
+        this.password = password;
+        this.role = role;
+    }
+
+    /**
+     * 登录验证
+     * @param username 用户名
+     * @param password 密码
+     * @return 返回用户对象或null
+     */
+    public static User login(String username, String password) {
+        String[][] users = {
+                {"张三1", "123", "小学"}, {"张三2", "123", "小学"}, {"张三3", "123", "小学"},
+                {"李四1", "123", "初中"}, {"李四2", "123", "初中"}, {"李四3", "123", "初中"},
+                {"王五1", "123", "高中"}, {"王五2", "123", "高中"}, {"王五3", "123", "高中"}
+        };
+
+        for (String[] user : users) {
+            if (user[0].equals(username) && user[1].equals(password)) {
+                return new User(username, password, user[2]);
+            }
+        }
+        return null;
+    }
+
+    /**
+     * 获取用户角色
+     * @return 用户角色
+     */
+    public String getRole() {
+        return this.role;
+    }
+
+    /**
+     * 获取用户名
+     * @return 用户名
+     */
+    public String getUsername() {
+        return this.username;
+    }
+}