feat:修改

zhijiayun-quiz/src/main/java/com/xuekairui/quiz/service/impl/StudyBookServiceImpl.java

@@ -84,6 +84,12 @@ public class StudyBookServiceImpl implements StudyBookService {
                         .eq(QuizChapter::getSubjectId, subjectId)
                         .orderByAsc(QuizChapter::getSort)
         );
+        // 后台在"科目"下新增的章 parentId=科目ID；树构建以 0 为根，统一归一化
+        for (QuizChapter ch : chapters) {
+            if (subjectId.equals(ch.getParentId())) {
+                ch.setParentId(0L);
+            }
+        }
 
         // 实时查询各考点题目数
         Map<Long, Integer> directCountMap = getDirectQuestionCounts();