feat: add chapter_sorting and chapter_searching by dart (#497)

* feat: add chapter_sorting by dart

* feat: add chapter_searching by dart

---------

Co-authored-by: huangjianqing <huangjianqing@52tt.com>

codes/dart/utils/list_node.dart

@@ -18,3 +18,14 @@ class ListNode {
     return 'ListNode{val: $val, next: $next}';
   }
 }
+
+/* Generate a linked list with a vector */
+ListNode? listToLinkedList(List<int> list) {
+  ListNode dum = ListNode(0);
+  ListNode? head = dum;
+  for (int val in list) {
+    head?.next = ListNode(val);
+    head = head?.next;
+  }
+  return dum.next;
+}