diff --git a/tree/tree.go b/tree/tree.go
index 747e778..aa52839 100644
--- a/tree/tree.go
+++ b/tree/tree.go
@@ -4,17 +4,7 @@ import (
 	"cmp"
 )
 
-type NodeSlice[I cmp.Ordered, E any] []NodeTree[I, E]
 
-func (nodes NodeSlice[T, E]) Len() int {
-	return len(nodes)
-}
-func (nodes NodeSlice[T, E]) Less(i, j int) bool {
-	return nodes[i].GetId() < nodes[j].GetId()
-}
-func (nodes NodeSlice[T, E]) Swap(i, j int) {
-	nodes[i], nodes[j] = nodes[j], nodes[i]
-}
 
 type NodeTree[I cmp.Ordered, T any] interface {
 	GetId() I
@@ -27,39 +17,37 @@ type Node[I cmp.Ordered, U NodeTree[I, U]] interface {
 	MapTree() U
 }
 
-// IntoTree 列表转树, 切片无children, map转换
+// IntoTree 列表转树, 切片无children
 // 两次循环就可以获取列表转树
 func IntoTree[I cmp.Ordered, E Node[I, U], U NodeTree[I, U]](rows []E, rootPid I) []U {
 	nodes := make([]U, 0, len(rows))
 	nodeMaps := make(map[I]U)
 	for _, v := range rows {
-		vv := v.MapTree()
-		nodes = append(nodes, vv)
-		nodeMaps[v.MapId()] = vv
+		e := v.MapTree()
+		nodes = append(nodes, e)
+		nodeMaps[v.MapId()] = e
 	}
 	return intoTree(nodeMaps, nodes, rootPid)
 }
 
-// IntoTree 列表转树
+// IntoTree 列表转树, 切片有children
 // 两次循环就可以获取列表转树
 func IntoTree2[T cmp.Ordered, E NodeTree[T, E]](rows []E, rootPid T) []E {
 	nodeMaps := make(map[T]E)
-	for _, v := range rows {
-		vv := v
-		nodeMaps[v.GetId()] = vv
+	for _, e := range rows {
+		nodeMaps[e.GetId()] = e
 	}
 	return intoTree(nodeMaps, rows, rootPid)
 }
 
 func intoTree[T cmp.Ordered, E NodeTree[T, E]](nodeMaps map[T]E, rows []E, rootPid T) []E {
 	var root []E
-	for _, v := range rows {
-		node := v
-		pid := node.GetPid()
+	for _, e := range rows {
+		pid := e.GetPid()
 		if pid == rootPid {
-			root = append(root, node)
+			root = append(root, e)
 		} else if parent, exists := nodeMaps[pid]; exists {
-			parent.AppendChildren(node)
+			parent.AppendChildren(e)
 		}
 	}
 	return root
diff --git a/tree/tree_sort.go b/tree/tree_sort.go
new file mode 100644
index 0000000..ab633fc
--- /dev/null
+++ b/tree/tree_sort.go
@@ -0,0 +1,15 @@
+package tree
+
+import "cmp"
+
+type NodeSlice[I cmp.Ordered, E any] []NodeTree[I, E]
+
+func (nodes NodeSlice[T, E]) Len() int {
+	return len(nodes)
+}
+func (nodes NodeSlice[T, E]) Less(i, j int) bool {
+	return nodes[i].GetId() < nodes[j].GetId()
+}
+func (nodes NodeSlice[T, E]) Swap(i, j int) {
+	nodes[i], nodes[j] = nodes[j], nodes[i]
+}
diff --git a/tree/tree_test.go b/tree/tree_test.go
index 2644f98..fef312b 100644
--- a/tree/tree_test.go
+++ b/tree/tree_test.go
@@ -7,13 +7,19 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+var _ Node[int, *DeptTree] = (*Dept)(nil)
+var _ NodeTree[int, *DeptTree] = (*DeptTree)(nil)
+
 type Dept struct {
 	Id   int
 	Pid  int
 	Name string
 }
 
+// MapId implements Node.
 func (d *Dept) MapId() int { return d.Id }
+
+// MapTree implements Node.
 func (d *Dept) MapTree() *DeptTree {
 	return &DeptTree{
 		Dept:     d,
@@ -26,9 +32,13 @@ type DeptTree struct {
 	Children []*DeptTree
 }
 
-func (d *DeptTree) GetId() int  { return d.Id }
+// GetId implements NodeTree.
+func (d *DeptTree) GetId() int { return d.Id }
+
+// GetPid implements NodeTree.
 func (d *DeptTree) GetPid() int { return d.Pid }
 
+// AppendChildren implements NodeTree.
 func (d *DeptTree) AppendChildren(v *DeptTree) {
 	d.Children = append(d.Children, v)
 }
@@ -48,8 +58,19 @@ var arr = []*Dept{
 }
 
 func TestTree(t *testing.T) {
-	vv := IntoTree(arr, 0)
-	v, err := json.MarshalIndent(vv, " ", "  ")
+	gotTree1 := IntoTree(arr, 0)
+	tree1, err := json.MarshalIndent(gotTree1, " ", "  ")
+	require.NoError(t, err)
+
+	arrTree := make([]*DeptTree, 0, len(arr))
+	for _, v := range arr {
+		vv := *v
+		arrTree = append(arrTree, vv.MapTree())
+	}
+
+	gotTree2 := IntoTree2(arrTree, 0)
+	tree2, err := json.MarshalIndent(gotTree2, " ", "  ")
 	require.NoError(t, err)
-	t.Log(string(v))
+
+	require.Equal(t, tree2, tree1)
 }