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src/main/java/com/example/myapp/service/AbstractQuestionSeting.java

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+// AbstractQuestionSeting.java
+package com.example.myapp.service;
+
+import com.example.myapp.model.Expression;
+import java.util.Random;
+
+public abstract class AbstractQuestionSeting implements QuestionSeting {
+  protected Random rand = new Random();
+
+  // 只生成整数（1-50）
+  protected String getRandomNumber() {
+    int num = 1 + rand.nextInt(50);
+    return String.valueOf(num);
+  }
+
+  // 生成完全平方数（用于开方运算）
+  protected String getPerfectSquare() {
+    int base = 1 + rand.nextInt(12); // 1-12的平方
+    int square = base * base;
+    return String.valueOf(square);
+  }
+
+  // 生成适合开方的数（完全平方数）
+  protected String getNumberForSqrt() {
+    // 80%概率生成完全平方数，20%概率生成普通数
+    //if (rand.nextDouble() < 1) {
+      return getPerfectSquare();
+//    } else {
+//      return getRandomNumber();
+//    }
+  }
+
+  protected String getRandomOperator() {
+    String[] ops = {"+", "-", "*", "/"};
+    return ops[rand.nextInt(ops.length)];
+  }
+
+  protected int getPriority(String op) {
+    if (op == null) return 3;
+    switch (op) {
+      case "+":
+      case "-":
+        return 1;
+      case "*":
+      case "/":
+        return 2;
+      case "²":
+      case "√":
+      case "sin":
+      case "cos":
+      case "tan":
+        return 3;
+      default:
+        return 0;
+    }
+  }
+
+  // 解析数字字符串为double
+  protected double parseNumber(String numStr) {
+    return Double.parseDouble(numStr);
+  }
+
+  // 格式化结果为字符串，如果是整数显示整数，小数显示小数
+  protected String formatResult(double value) {
+    if (value == (int) value) {
+      return String.valueOf((int) value);
+    } else {
+      // 保留2位小数，但去除末尾的0
+      String formatted = String.format("%.2f", value);
+      if (formatted.endsWith(".00")) {
+        return formatted.substring(0, formatted.length() - 3);
+      } else if (formatted.endsWith("0")) {
+        return formatted.substring(0, formatted.length() - 1);
+      }
+      return formatted;
+    }
+  }
+
+  public abstract String addParenthesesIfNeeded(Expression child, String parentOp, boolean isRightChild);
+}