Merge pull request '3' (#3) from develop into main

src/BracketManager.java

@@ -0,0 +1,148 @@
+import java.util.List;
+import java.util.Random;
+
+/**
+ * 负责生成并添加括号
+ */
+public class BracketManager {
+  private static final Random RANDOM = new Random();
+  
+  /**
+   * 根据元素个数选择括号对数
+   * 3 -> 80% 1对 20%0对
+   * 4 -> 90% 1对 10%2对
+   * 5 -> 50% 1对 50%2对
+   */
+  public int decideParenthesesPairs(int numCount) {
+    return switch (numCount) {
+      case 3 -> RANDOM.nextDouble() < 0.8 ? 1 : 0;
+      case 4 -> RANDOM.nextDouble() < 0.9 ? 1 : 2;
+      case 5 -> RANDOM.nextDouble() < 0.5 ? 1 : 2;
+      default -> 0;
+    };
+  }
+  
+  // 添加括号
+  public String addParentheses(String expression, int pairs, List<Integer> numPositions) {
+    String[] tokens = expression.split(" ");
+    int numCount = numPositions.size();
+    boolean[] markLeft = new boolean[numCount];
+    boolean[] markRight = new boolean[numCount];
+    
+    generateBracketPositions(numCount, numPositions, pairs, tokens, markLeft, markRight);
+    String result = insertBrackets(tokens, markLeft, markRight);
+    return validateParentheses(result) ? result : expression;
+  }
+  
+  //计算生成括号的位置
+  private void generateBracketPositions(int numCount, List<Integer> numPositions, int pairs, String[] tokens,
+                                        boolean[] markLeft, boolean[] markRight) {
+    int attempts = 0;
+    for (int p = 0; p < pairs && attempts < 50; p++, attempts++) {
+      boolean placed = false;
+      for (int tries = 0; tries < 50 && !placed; tries++) {
+        int start = RANDOM.nextInt(numCount - 1);
+        int end = start + 1 + RANDOM.nextInt(numCount - start - 1);
+        if (end >= numCount) end = numCount - 1;
+        
+        // 20%概率尝试嵌套在已有括号内部
+        if (RANDOM.nextDouble() < 0.2) {
+          for (int i = 0; i < numCount; i++) {
+            if (markLeft[i]) {
+              start = i;
+              end = i + RANDOM.nextInt(numCount - i);
+              break;
+            }
+          }
+        }
+        
+        if (canPlaceBracket(start, end, markLeft, markRight, numPositions, tokens)) {
+          markLeft[start] = true;
+          markRight[end] = true;
+          placed = true;
+        }
+      }
+    }
+  }
+  
+  //检测添加括号的合法性
+  private boolean canPlaceBracket(int start, int end, boolean[] markLeft, boolean[] markRight,
+                                  List<Integer> numPositions, String[] tokens) {
+    if (isOuterMostBracket(start, end, markLeft.length)) return false;
+    if (isInvalidOverlap(start, end, markLeft, markRight)) return false;
+    return isValidBracketRange(tokens, numPositions, start, end);
+  }
+  
+  //避免最外层括号
+  private boolean isOuterMostBracket(int start, int end, int numCount) {
+    return start == 0 && end == numCount - 1;
+  }
+  
+  //允许嵌套但禁止交叉
+  private boolean isInvalidOverlap(int start, int end, boolean[] markLeft, boolean[] markRight) {
+    for (int i = start; i <= end; i++) {
+      // start/end可重合，内部禁止已有左右括号
+      if ((i != start && markLeft[i]) || (i != end && markRight[i])) return true;
+    }
+    return false;
+  }
+  
+  //检测括号是否有意义（优先级）
+  private boolean isValidBracketRange(String[] tokens, List<Integer> numPositions, int start, int end) {
+    int opStart = numPositions.get(start) + 1;
+    int opEnd = numPositions.get(end) - 1;
+    String firstOp = null;
+    boolean hasHigherOuterOp = false;
+    
+    for (int i = opStart; i <= opEnd; i += 2) {
+      if (!isNumber(tokens[i])) {
+        if (firstOp == null) firstOp = tokens[i];
+        else if (isDifferentPriority(firstOp, tokens[i])) {
+          hasHigherOuterOp = true;
+          break;
+        }
+      }
+    }
+    return hasHigherOuterOp || firstOp == null;
+  }
+  
+  //比较运算符优先级
+  private boolean isDifferentPriority(String op1, String op2) {
+    int p1 = (op1.equals("+") || op1.equals("-")) ? 1 : 2;
+    int p2 = (op2.equals("+") || op2.equals("-")) ? 1 : 2;
+    return p1 != p2;
+  }
+  
+  //插入操作
+  private String insertBrackets(String[] tokens, boolean[] markLeft, boolean[] markRight) {
+    StringBuilder sb = new StringBuilder();
+    int numIndex = 0;
+    for (String token : tokens) {
+      if (isNumber(token)) {
+        if (markLeft[numIndex]) sb.append("( ");
+        sb.append(token);
+        if (markRight[numIndex]) sb.append(" )");
+        numIndex++;
+      } else {
+        sb.append(" ").append(token).append(" ");
+      }
+    }
+    return sb.toString();
+  }
+  
+  //检查括号是否缺失
+  private boolean validateParentheses(String expr) {
+    int balance = 0;
+    for (char c : expr.toCharArray()) {
+      if (c == '(') balance++;
+      if (c == ')') balance--;
+      if (balance < 0) return false;
+    }
+    return balance == 0;
+  }
+  
+  private boolean isNumber(String token) {
+    try { Integer.parseInt(token); return true; }
+    catch (NumberFormatException e) { return false; }
+  }
+}

src/ExamSystem.java

@@ -1,7 +1,11 @@
 import java.util.Scanner;
 
+/**
+ * 系统界面
+ */
 public class ExamSystem {
   private final Scanner scanner = new Scanner(System.in);
+  
   public Users login() {
     Users users = null;
     while (users == null) {
@@ -22,42 +26,57 @@ public class ExamSystem {
   public void generateProblems(Users users) {
     while (true) {
       String input = scanner.nextLine().trim();
-      if (input.equals("-1")) {
-        break;
-      }
+      if (input.equals("-1")) break;
       
-      ProblemsGenerator generator = switch (users.getType()) {
-        case "小学" -> new PrimaryProblem();
-        case "初中" -> new JuniorProblem();
-        case "高中" -> new SeniorProblem();
-        default -> null;
-      };
-      
-      if (input.startsWith("切换为")) {
-        String target = input.replace("切换为", "");
-        if (target.equals("小学") || target.equals("初中") || target.equals("高中")) {
-          users = new Users(users.getName(), users.getPassword(), target);
-          System.out.print("系统提示：准备生成" + users.getType()
-              + "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）：");
-        } else {
-          System.out.println("请输入小学、初中和高中三个选项中的一个");
-        }
+      Users newUsers = handleSwitchType(input, users);
+      if (newUsers != null) {
+        users = newUsers;
         continue;
       }
       
-      try {
-        int num = Integer.parseInt(input);
-        if (num >= 10 && num <= 30 && generator != null) {
-          Generator.generate(users, num, generator);
-        } else {
-          System.out.println("请输入 10-30 之间的数字");
-        }
-      } catch (NumberFormatException e) {
-        System.out.println("请输入小学、初中和高中三个选项中的一个");
-      }
-      
-      System.out.print("准备生成" + users.getType()
+      ProblemsGenerator generator = getGenerator(users.getType());
+      handleGenerate(input, users, generator);
+    }
+  }
+  
+  private ProblemsGenerator getGenerator(String type) {
+    return switch (type) {
+      case "小学" -> new PrimaryProblem();
+      case "初中" -> new JuniorProblem();
+      case "高中" -> new SeniorProblem();
+      default -> null;
+    };
+  }
+  
+  private Users handleSwitchType(String input, Users users) {
+    if (!input.startsWith("切换为")) return null;
+    
+    String target = input.replace("切换为", "");
+    if (target.equals("小学") || target.equals("初中") || target.equals("高中")) {
+      Users newUsers = new Users(users.getName(), users.getPassword(), target);
+      System.out.print("系统提示：准备生成" + newUsers.getType()
           + "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）：");
+      return newUsers;
+    } else {
+      System.out.println("请输入小学、初中和高中三个选项中的一个");
+      return null;
     }
   }
+  
+  private void handleGenerate(String input, Users users, ProblemsGenerator generator) {
+    try {
+      int num = Integer.parseInt(input);
+      if (num >= 10 && num <= 30 && generator != null) {
+        Generator.generate(users, num, generator);
+      } else {
+        System.out.println("请输入 10-30 之间的数字");
+      }
+    } catch (NumberFormatException e) {
+      System.out.println("请输入小学、初中和高中三个选项中的一个");
+    }
+    
+    System.out.print("准备生成" + users.getType()
+        + "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）：");
+  }
+  
 }

src/ExpressionBuilder.java

@@ -0,0 +1,51 @@
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+
+public class ExpressionBuilder {
+  private static final Random RANDOM = new Random();
+  private static final String[] OPERATORS = {"+", "-", "*", "/"};
+  
+  // 生成基础四则运算表达式
+  public String generateBasicExpression(int count) {
+    StringBuilder sb = new StringBuilder();
+    for (int i = 0; i < count; i++) {
+      sb.append(RANDOM.nextInt(100) + 1);
+      if (i < count - 1) {
+        sb.append(" ").append(OPERATORS[RANDOM.nextInt(OPERATORS.length)]).append(" ");
+      }
+    }
+    return sb.toString();
+  }
+  
+  // 获取表达式中数字的位置
+  public List<Integer> getNumberPositions(String expression) {
+    String[] tokens = expression.split(" ");
+    List<Integer> positions = new ArrayList<>();
+    for (int i = 0; i < tokens.length; i++) {
+      if (isNumber(tokens[i])) positions.add(i);
+    }
+    return positions;
+  }
+  
+  // 检查是否存在除零
+  public boolean hasDivideByZero(String expression) {
+    String[] tokens = expression.split(" ");
+    for (int i = 0; i < tokens.length - 1; i++) {
+      if (tokens[i].equals("/")) {
+        try {
+          if (Integer.parseInt(tokens[i + 1]) == 0) return true;
+        } catch (NumberFormatException e) {
+          //
+        }
+      }
+    }
+    return false;
+  }
+  
+  //判断是否为数字位
+  private boolean isNumber(String token) {
+    try { Integer.parseInt(token); return true; }
+    catch (NumberFormatException e) { return false; }
+  }
+}

src/Generator.java

@@ -1,31 +1,96 @@
+import java.io.File;
 import java.io.FileWriter;
 import java.io.IOException;
 import java.time.LocalDateTime;
 import java.time.format.DateTimeFormatter;
+import java.util.HashSet;
+import java.util.Scanner;
+import java.util.Set;
 
+/**
+ * 题目生成器，支持历史查重和文件保存
+ */
 public class Generator {
+  
+  //生成题目并保存到用户文件夹
   public static void generate(Users users, int count, ProblemsGenerator problemsGenerator) {
+    Set<String> history = loadHistory(users);
     StringBuilder builder = new StringBuilder();
+    
     for (int i = 1; i <= count; i++) {
-      builder.append(i).append(". ").append(problemsGenerator.generate()).append("\n\n");
+      String problem;
+      int tries = 0;
+      do {
+        problem = problemsGenerator.generate();
+        tries++;
+        if (tries >= 20) {
+          System.out.println("警告：尝试 20 次仍未生成新题目，可能题目库有限。");
+          break;
+        }
+      } while (history.contains(problem));
+      
+      history.add(problem);
+      builder.append(i).append(". ").append(problem).append("\n\n");
     }
+    
     save(users, builder.toString());
     System.out.println("题目生成完成。");
   }
   
+  /**
+   * 读取用户历史题目
+   */
+  private static Set<String> loadHistory(Users users) {
+    Set<String> history = new HashSet<>();
+    String safeName = users.getName().replaceAll("[^\\u4e00-\\u9fa5a-zA-Z0-9_]", "_");
+    String folder = "doc/" + safeName;
+    File dir = new File(folder);
+    if (!dir.exists()) return history;
+    
+    File[] files = dir.listFiles((d, name) -> name.endsWith(".txt"));
+    if (files != null) {
+      for (File f : files) {
+        try (Scanner sc = new Scanner(f)) {
+          while (sc.hasNextLine()) {
+            String line = sc.nextLine().trim();
+            if (!line.isEmpty() && Character.isDigit(line.charAt(0))) {
+              int dot = line.indexOf('.');
+              if (dot != -1) line = line.substring(dot + 1).trim();
+              history.add(line);
+            }
+          }
+        } catch (IOException e) {
+          e.printStackTrace();
+          System.out.println("读取历史题目失败：" + e.getMessage());
+        }
+      }
+    }
+    
+    return history;
+  }
+  
+  /**
+   * 保存生成题目到文件
+   */
   private static void save(Users users, String content) {
     try {
-      String folder = "doc/" + users.getName();
-      java.io.File dir = new java.io.File(folder);
-      if (!dir.exists()) {
-        dir.mkdirs();
+      String safeName = users.getName().replaceAll("[^\\u4e00-\\u9fa5a-zA-Z0-9_]", "_");
+      String folder = "doc/" + safeName;
+      File dir = new File(folder);
+      if (!dir.exists() && !dir.mkdirs()) {
+        System.out.println("无法创建目录: " + folder);
+        return;
       }
+      
       String filename = LocalDateTime.now()
-          .format(DateTimeFormatter.ofPattern("yyyy-MM-dd-HH-mm-ss")) + ".txt";
-      FileWriter writer = new FileWriter(folder + "/" + filename);
-      writer.write(content);
-      writer.close();
+          .format(DateTimeFormatter.ofPattern("yyyy-MM-dd-HH-mm-ss"))
+          + "-" + (int) (Math.random() * 1000) + ".txt";
+      
+      try (FileWriter writer = new FileWriter(folder + "/" + filename)) {
+        writer.write(content);
+      }
     } catch (IOException e) {
+      e.printStackTrace();
       System.out.println("保存失败：" + e.getMessage());
     }
   }

src/JuniorProblem.java

@@ -1,51 +1,36 @@
+import java.util.List;
 import java.util.Random;
 
+/**
+ * 生成初中题目
+ */
 public class JuniorProblem implements ProblemsGenerator {
   private static final Random RANDOM = new Random();
-  private static final String[] OPERATORS = {"+", "-", "*", "/"};
-  private static final String[] POW_OPERATORS = {"√", "^2"};
+  private final BracketManager bracketManager = new BracketManager();
+  private final PowerManager powerManager = new PowerManager();
+  private final ExpressionBuilder expressionBuilder = new ExpressionBuilder();
   
   @Override
   public String generate() {
-    String primaryExpr = generatePrimaryExpression();
-    return addPowerOperators(primaryExpr);
-  }
-  
-  private String generatePrimaryExpression() {
-    int count = RANDOM.nextInt(4) + 2;
-    StringBuilder sb = new StringBuilder();
-    
-    for (int i = 0; i < count; i++) {
-      sb.append(RANDOM.nextInt(100) + 1);
-      if (i < count - 1) {
-        sb.append(" ").append(OPERATORS[RANDOM.nextInt(OPERATORS.length)]).append(" ");
-      }
-    }
-    return sb.toString();
-  }
-  
-  private String addPowerOperators(String expr) {
-    String[] parts = expr.split(" ");
-    boolean hasPower = false;
-    
-    for (int i = 0; i < parts.length; i++) {
-      if (parts[i].matches("\\d+") && (!hasPower || RANDOM.nextBoolean())) {
-        String op = POW_OPERATORS[RANDOM.nextInt(POW_OPERATORS.length)];
-        parts[i] = op.equals("√") ? "√" + parts[i] : parts[i] + "^2";
-        hasPower = true;
-      }
-    }
-    
-    if (!hasPower) {
-      for (int i = 0; i < parts.length; i++) {
-        if (parts[i].matches("\\d+")) {
-          String op = POW_OPERATORS[RANDOM.nextInt(POW_OPERATORS.length)];
-          parts[i] = op.equals("√") ? "√" + parts[i] : parts[i] + "^2";
-          break;
+    String expression;
+    boolean hasPower;
+    do {
+      int numCount = RANDOM.nextInt(5) + 1;
+      expression = expressionBuilder.generateBasicExpression(numCount);
+      List<Integer> numPositions = expressionBuilder.getNumberPositions(expression);
+      
+      if (RANDOM.nextDouble() < 0.8) {
+        int pairs = bracketManager.decideParenthesesPairs(numCount);
+        if (pairs > 0) {
+          expression = bracketManager.addParentheses(expression, pairs, numPositions);
         }
       }
-    }
+      
+      // 添加幂运算并检查添加是否成功
+      expression = powerManager.addPowerOperations(expression, numPositions);
+      hasPower = expression.contains("^2") || expression.contains("√");
+    } while (expressionBuilder.hasDivideByZero(expression) || !hasPower);
     
-    return String.join(" ", parts);
+    return expression;
   }
-}
+}

src/Main.java

@@ -1,3 +1,6 @@
+/**
+ * 主程序
+ */
 public class Main {
   public static void main(String[] args) {
     ExamSystem system = new ExamSystem();
@@ -8,4 +11,4 @@ public class Main {
       system.generateProblems(users);
     }
   }
-}
+}

src/PowerManager.java

@@ -0,0 +1,95 @@
+import java.util.List;
+import java.util.Random;
+
+/**
+ * 负责添加幂运算
+ */
+public class PowerManager {
+  private static final Random RANDOM = new Random();
+  
+  // 普通幂运算
+  public String addPowerOperations(String expression, List<Integer> numPositions) {
+    if (numPositions.isEmpty()) return expression;
+    
+    String[] tokens = expression.split(" ");
+    int targetIndex = chooseTargetIndex(tokens, numPositions, null);
+    
+    if (targetIndex != -1) {
+      tokens[targetIndex] = applyPower(tokens[targetIndex], tokens, targetIndex);
+    }
+    
+    return String.join(" ", tokens);
+  }
+  
+  // 避免加在 trig 已占用的位置，同时避免加在运算符右边
+  public String addPowerOperationsAvoid(String expression, List<Integer> numPositions, List<Integer> trigPositions) {
+    if (numPositions.isEmpty()) return expression;
+    
+    String[] tokens = expression.split(" ");
+    int targetIndex = chooseTargetIndex(tokens, numPositions, trigPositions);
+    
+    if (targetIndex != -1) {
+      tokens[targetIndex] = applyPower(tokens[targetIndex], tokens, targetIndex);
+    }
+    
+    return String.join(" ", tokens);
+  }
+  
+  // 选择合适的位置加幂运算
+  private int chooseTargetIndex(String[] tokens, List<Integer> numPositions, List<Integer> avoidPositions) {
+    for (int tries = 0; tries < 20; tries++) {
+      int idx = numPositions.get(RANDOM.nextInt(numPositions.size()));
+      
+      if ((avoidPositions == null || !avoidPositions.contains(idx)) && canApplyPower(tokens, idx)) {
+        return idx;
+      }
+    }
+    return -1;
+  }
+  
+  // 检查该位置是否可以加幂运算
+  private boolean canApplyPower(String[] tokens, int index) {
+    if (!isNumber(tokens[index])) return false;
+    if (tokens[index].contains("^") || tokens[index].contains("√")) return false; // 避免重复幂运算
+    
+    // 不能加在运算符右边
+    if (index > 0) {
+      String prev = tokens[index - 1];
+      if (prev.equals("/") || prev.equals("*") || prev.equals("+") || prev.equals("-")) {
+        return false;
+      }
+    }
+    return true;
+  }
+  
+  // 应用平方或开方（根号放左括号左侧，平方放右括号右侧）
+  private String applyPower(String token, String[] tokens, int index) {
+    boolean useSqrt = RANDOM.nextBoolean();
+    
+    if (useSqrt) {
+      // 根号放在左括号左侧，如果前面是左括号，则放在括号左边
+      if (index > 0 && tokens[index - 1].equals(")")) {
+        return "√" + token; // 特殊情况，仍然放数字前
+      }
+      if (index > 0 && tokens[index - 1].equals("(")) {
+        return "√" + token;
+      }
+      return "√" + token;
+    } else {
+      // 平方放在右括号右侧，如果后面是右括号，则放在括号右边
+      if (index < tokens.length - 1 && tokens[index + 1].equals(")")) {
+        return token + "^2";
+      }
+      return token + "^2";
+    }
+  }
+  
+  private boolean isNumber(String token) {
+    try {
+      Integer.parseInt(token);
+      return true;
+    } catch (NumberFormatException e) {
+      return false;
+    }
+  }
+}

src/PrimaryProblem.java

@@ -1,44 +1,29 @@
+import java.util.List;
 import java.util.Random;
 
+/**
+ * 生成小学题目
+ */
 public class PrimaryProblem implements ProblemsGenerator {
   private static final Random RANDOM = new Random();
-  private static final String[] OPERATORS = {"+", "-", "*", "/"};
+  private final BracketManager bracketManager = new BracketManager();
+  private final ExpressionBuilder expressionBuilder = new ExpressionBuilder();
   
   @Override
   public String generate() {
-    int count = RANDOM.nextInt(4) + 2;
-    StringBuilder sb = new StringBuilder();
-    
-    boolean addParentheses = count >= 3 && RANDOM.nextDouble() < 0.5;
-    if (addParentheses) {
-      int parenCount = RANDOM.nextInt(count - 2) + 2;
-      int startPos = RANDOM.nextInt(count - parenCount + 1);
-      
-      for (int i = 0; i < count; i++) {
-        if (i == startPos) {
-          sb.append("( ");
-        }
-        
-        int num = RANDOM.nextInt(100) + 1;
-        sb.append(num);
-        
-        if (i == startPos + parenCount - 1) {
-          sb.append(" )");
-        }
-        
-        if (i < count - 1) {
-          sb.append(" ").append(OPERATORS[RANDOM.nextInt(OPERATORS.length)]).append(" ");
-        }
-      }
-    } else {
-      for (int i = 0; i < count; i++) {
-        int num = RANDOM.nextInt(100) + 1;
-        sb.append(num);
-        if (i < count - 1) {
-          sb.append(" ").append(OPERATORS[RANDOM.nextInt(OPERATORS.length)]).append(" ");
-        }
+    String expression;
+    do {
+      int numCount = 2 + RANDOM.nextInt(4);
+      expression = expressionBuilder.generateBasicExpression(numCount);
+
+      List<Integer> numPositions = expressionBuilder.getNumberPositions(expression);
+      int pairs = bracketManager.decideParenthesesPairs(numCount);
+      if (pairs > 0) {
+        expression = bracketManager.addParentheses(expression, pairs, numPositions);
       }
-    }
-    return sb.toString();
+      
+    } while (expressionBuilder.hasDivideByZero(expression));
+    
+    return expression;
   }
-}
+}

src/SeniorProblem.java

@@ -1,107 +1,43 @@
+import java.util.List;
 import java.util.Random;
 
+/**
+ * 生成高中题目
+ */
 public class SeniorProblem implements ProblemsGenerator {
   private static final Random RANDOM = new Random();
-  private static final String[] OPERATORS = {"+", "-", "*", "/"};
-  private static final String[] POW_OPERATORS = {"√", "^2"};
-  private static final String[] TRIG_OPERATORS = {"sin", "cos", "tan"};
+  private final BracketManager bracketManager = new BracketManager();
+  private final PowerManager powerManager = new PowerManager();
+  private final TrigManager trigManager = new TrigManager();
+  private final ExpressionBuilder expressionBuilder = new ExpressionBuilder();
   
   @Override
   public String generate() {
-    String primaryExpression = generatePrimaryExpression();
-    
-    return addHighSchoolOperators(primaryExpression);
-  }
-  
-  private String generatePrimaryExpression() {
-    int count = RANDOM.nextInt(4) + 2;
-    StringBuilder sb = new StringBuilder();
-    
-    for (int i = 0; i < count; i++) {
-      int num = RANDOM.nextInt(100) + 1;
-      sb.append(num);
-      if (i < count - 1) {
-        sb.append(" ").append(OPERATORS[RANDOM.nextInt(OPERATORS.length)]).append(" ");
-      }
-    }
-    return sb.toString();
-  }
-  
-  private String addHighSchoolOperators(String primaryExpression) {
-    String[] parts = primaryExpression.split(" ");
-    StringBuilder result = new StringBuilder();
-    boolean hasTrigonometry = false;
-    boolean hasAlgebra = false;
-    
-    for (int i = 0; i < parts.length; i++) {
-      String part = parts[i];
+    String expression;
+    boolean hasTrig;
+    do {
+      int numCount = RANDOM.nextInt(5) + 1;
+      expression = expressionBuilder.generateBasicExpression(numCount);
+      List<Integer> numPositions = expressionBuilder.getNumberPositions(expression);
       
-      if (isNumber(part)) {
-        if (!hasTrigonometry || RANDOM.nextDouble() < 0.6) {
-          part = applyTrigOperator(part);
-          hasTrigonometry = true;
-        }
-        else if (RANDOM.nextDouble() < 0.3) {
-          part = applyAlgebraOperator(part);
-          hasAlgebra = true;
+      if (RANDOM.nextDouble() < 0.8) {
+        int pairs = bracketManager.decideParenthesesPairs(numCount);
+        if (pairs > 0) {
+          expression = bracketManager.addParentheses(expression, pairs, numPositions);
         }
       }
       
-      result.append(part);
-      if (i < parts.length - 1) {
-        result.append(" ");
-      }
-    }
-    
-    if (!hasTrigonometry) {
-      return addTrigonometryForced(result.toString());
-    }
-    
-    return result.toString();
-  }
-  
-  private boolean isNumber(String str) {
-    try {
-      Integer.parseInt(str);
-      return true;
-    } catch (NumberFormatException e) {
-      return false;
-    }
-  }
-  
-  private String applyTrigOperator(String number) {
-    String operator = TRIG_OPERATORS[RANDOM.nextInt(TRIG_OPERATORS.length)];
-    int num = Integer.parseInt(number);
-    int angle = generateValidAngle(operator);
-    return operator + angle + "°";
-  }
-  
-  private String applyAlgebraOperator(String number) {
-    String operator = POW_OPERATORS[RANDOM.nextInt(POW_OPERATORS.length)];
-    int num = Integer.parseInt(number);
-    return operator.equals("√") ? "√" + num : num + "^2";
-  }
-  
-  private int generateValidAngle(String trigOp) {
-    int angle = RANDOM.nextInt(100) + 1;
-    if (trigOp.equals("tan")) {
-      while (angle == 90) {
-        angle = RANDOM.nextInt(100) + 1;
-      }
-    }
-    return angle;
-  }
-  
-  private String addTrigonometryForced(String expression) {
-    String[] parts = expression.split(" ");
-    
-    for (int i = 0; i < parts.length; i++) {
-      if (isNumber(parts[i])) {
-        parts[i] = applyTrigOperator(parts[i]);
-        break;
+      // 添加三角函数并检查是否存在
+      expression = trigManager.addTrigOperations(expression, numPositions);
+      List<Integer> trigPositions = expressionBuilder.getNumberPositions(expression);
+      hasTrig = expression.contains("sin") || expression.contains("cos") || expression.contains("tan");
+      
+      // 40% 概率加幂运算，避免与 trig 重叠
+      if (RANDOM.nextDouble() < 0.4) {
+        expression = powerManager.addPowerOperationsAvoid(expression, numPositions, trigPositions);
       }
-    }
+    } while (expressionBuilder.hasDivideByZero(expression) || !hasTrig);
     
-    return String.join(" ", parts);
+    return expression;
   }
-}
+}

src/TrigManager.java

@@ -0,0 +1,70 @@
+import java.util.List;
+import java.util.Random;
+
+/**
+ * 负责添加三角函数
+ */
+public class TrigManager {
+  private static final Random RANDOM = new Random();
+  private static final String[] TRIG_FUNCTIONS = {"sin", "cos", "tan"};
+  
+  //添加三角函数
+  public String addTrigOperations(String expression, List<Integer> numPositions) {
+    if (numPositions.isEmpty()) {
+      return expression;
+    }
+    
+    String[] tokens = expression.split(" ");
+    int targetIndex = chooseTargetIndex(numPositions, tokens);
+    if (targetIndex == -1) {
+      return expression;
+    }
+    
+    tokens[targetIndex] = applyTrig(tokens[targetIndex]);
+    return String.join(" ", tokens);
+  }
+  
+  //随机函数种类
+  private int chooseTargetIndex(List<Integer> numPositions, String[] tokens) {
+    for (int tries = 0; tries < 50; tries++) {
+      int idx = numPositions.get(RANDOM.nextInt(numPositions.size()));
+      if (canApplyTrig(tokens, idx)) {
+        return idx;
+      }
+    }
+    return -1;
+  }
+  
+  //检测三角函数是否合法
+  private boolean canApplyTrig(String[] tokens, int index) {
+    if (!isNumber(tokens[index])) {
+      return false;
+    }
+    int value = Integer.parseInt(tokens[index]);
+    
+    // 防止 tan(90)
+    if (value == 90 && RANDOM.nextInt(3) == 2) {
+      return false;
+    }
+    // cos(90) 不加在除法右边
+    if (index > 0 && tokens[index - 1].equals("/") && value == 90) {
+      return false;
+    }
+    return true;
+  }
+  
+  //添加操作
+  private String applyTrig(String token) {
+    String func = TRIG_FUNCTIONS[RANDOM.nextInt(TRIG_FUNCTIONS.length)];
+    return func + "(" + token + ")";
+  }
+  
+  private boolean isNumber(String token) {
+    try {
+      Integer.parseInt(token);
+      return true;
+    } catch (NumberFormatException e) {
+      return false;
+    }
+  }
+}

src/Users.java

@@ -1,44 +1,47 @@
-public class Users {
-  private final String name;
-  private final String password;
-  private final String type;
-  
-  private static final Users[] USERS = {
-      new Users("张三1", "123", "小学"),
-      new Users("张三2", "123", "小学"),
-      new Users("张三3", "123", "小学"),
-      new Users("李四1", "123", "初中"),
-      new Users("李四2", "123", "初中"),
-      new Users("李四3", "123", "初中"),
-      new Users("王五1", "123", "高中"),
-      new Users("王五2", "123", "高中"),
-      new Users("王五3", "123", "高中")
-  };
-  
-  public Users(String name, String password, String type) {
-    this.name = name;
-    this.password = password;
-    this.type = type;
-  }
-  
-  public String getType() {
-    return type;
-  }
-  
-  public String getName() {
-    return name;
-  }
-  
-  public String getPassword() {
-    return password;
-  }
-  
-  public static Users login(String name, String password) {
-    for (Users users : USERS) {
-      if (users.getName().equals(name) && users.getPassword().equals(password)) {
-        return users;
-      }
-    }
-    return null;
-  }
+/**
+ * 存储用户信息
+ */
+public class Users {
+  private final String name;
+  private final String password;
+  private final String type;
+  
+  private static final Users[] USERS = {
+      new Users("张三1", "123", "小学"),
+      new Users("张三2", "123", "小学"),
+      new Users("张三3", "123", "小学"),
+      new Users("李四1", "123", "初中"),
+      new Users("李四2", "123", "初中"),
+      new Users("李四3", "123", "初中"),
+      new Users("王五1", "123", "高中"),
+      new Users("王五2", "123", "高中"),
+      new Users("王五3", "123", "高中")
+  };
+  
+  public Users(String name, String password, String type) {
+    this.name = name;
+    this.password = password;
+    this.type = type;
+  }
+  
+  public String getType() {
+    return type;
+  }
+  
+  public String getName() {
+    return name;
+  }
+  
+  public String getPassword() {
+    return password;
+  }
+  
+  public static Users login(String name, String password) {
+    for (Users users : USERS) {
+      if (users.getName().equals(name) && users.getPassword().equals(password)) {
+        return users;
+      }
+    }
+    return null;
+  }
 }