diff --git a/pkg/tree.go b/pkg/tree.go
index 4b4f36d..8118d22 100644
--- a/pkg/tree.go
+++ b/pkg/tree.go
@@ -13,7 +13,7 @@ func Tree[T any](data []T, parent string, length int, pathFunc func(d T) string)
 	for _, v := range data {
 		path := pathFunc(v)
 		if len(path) < length {
-			return nil
+			return
 		}
 		p := path[:len(path)-length]
 		if p == parent {
@@ -25,3 +25,17 @@ func Tree[T any](data []T, parent string, length int, pathFunc func(d T) string)
 	}
 	return
 }
+
+// 拆分层级结构 A00001B00001C00001 拆分为 ["A00001","A00001B00001","A00001B00001C00001"]
+// length A00001 一个节点长度
+func Split(code string, length int) (res []string) {
+	if len(code) < length {
+		return
+	}
+
+	times := len(code) / length
+	for i := 0; i < times; i++ {
+		res = append(res, code[:len(code)-length*i])
+	}
+	return
+}