diff --git a/doc/unicstl.md b/doc/unicstl.md
index e69de29..974a4d0 100644
--- a/doc/unicstl.md
+++ b/doc/unicstl.md
@@ -0,0 +1,62 @@
+
+
+# tree
+日志
+```
+----- unicstl test -----
+
+
+----- test_tree_num -----
+----- insert -----
+insert = ( 5 ) size =  1 : ( 5 )
+insert = ( 2 ) size =  2 : ( 5 ) ( 2 )
+insert = ( 3 ) size =  3 : ( 3 ) ( 2 ) ( 5 )
+insert = ( 1 ) size =  4 : ( 3 ) ( 2 ) ( 1 ) ( 5 )
+insert = ( 7 ) size =  5 : ( 3 ) ( 2 ) ( 1 ) ( 5 ) ( 7 )
+insert = ( 8 ) size =  6 : ( 3 ) ( 2 ) ( 1 ) ( 7 ) ( 5 ) ( 8 )
+insert = ( 6 ) size =  7 : ( 3 ) ( 2 ) ( 1 ) ( 7 ) ( 5 ) ( 6 ) ( 8 )
+insert = ( 4 ) size =  8 : ( 3 ) ( 2 ) ( 1 ) ( 7 ) ( 5 ) ( 4 ) ( 6 ) ( 8 )
+insert = ( 9 ) size =  9 : ( 3 ) ( 2 ) ( 1 ) ( 7 ) ( 5 ) ( 4 ) ( 6 ) ( 8 ) ( 9 )
+insert = (10 ) size = 10 : ( 3 ) ( 2 ) ( 1 ) ( 7 ) ( 5 ) ( 4 ) ( 6 ) ( 9 ) ( 8 ) (10 )
+insert = (12 ) size = 11 : ( 7 ) ( 3 ) ( 2 ) ( 1 ) ( 5 ) ( 4 ) ( 6 ) ( 9 ) ( 8 ) (10 ) (12 )
+insert = (11 ) size = 12 : ( 7 ) ( 3 ) ( 2 ) ( 1 ) ( 5 ) ( 4 ) ( 6 ) ( 9 ) ( 8 ) (11 ) (10 ) (12 )
+insert = (15 ) size = 13 : ( 7 ) ( 3 ) ( 2 ) ( 1 ) ( 5 ) ( 4 ) ( 6 ) (11 ) ( 9 ) ( 8 ) (10 ) (12 ) (15 )
+insert = (14 ) size = 14 : ( 7 ) ( 3 ) ( 2 ) ( 1 ) ( 5 ) ( 4 ) ( 6 ) (11 ) ( 9 ) ( 8 ) (10 ) (14 ) (12 ) (15 )
+insert = (13 ) size = 15 : ( 7 ) ( 3 ) ( 2 ) ( 1 ) ( 5 ) ( 4 ) ( 6 ) (11 ) ( 9 ) ( 8 ) (10 ) (14 ) (12 ) (13 ) (15 )
+----- preorder -----
+( 7 ) ( 3 ) ( 2 ) ( 1 ) ( 5 ) ( 4 ) ( 6 ) (11 ) ( 9 ) ( 8 ) (10 ) (14 ) (12 ) (13 ) (15 )
+----- inorder -----
+( 1 ) ( 2 ) ( 3 ) ( 4 ) ( 5 ) ( 6 ) ( 7 ) ( 8 ) ( 9 ) (10 ) (11 ) (12 ) (13 ) (14 ) (15 )
+----- postorder -----
+( 1 ) ( 2 ) ( 4 ) ( 6 ) ( 5 ) ( 3 ) ( 8 ) (10 ) ( 9 ) (13 ) (12 ) (15 ) (14 ) (11 ) ( 7 )
+----- breadth -----
+( 7 ) ( 3 ) (11 ) ( 2 ) ( 5 ) ( 9 ) (14 ) ( 1 ) ( 4 ) ( 6 ) ( 8 ) (10 ) (12 ) (15 ) (13 )
+----- right priority -----
+----- preorder(right) -----
+( 7 ) (11 ) (14 ) (15 ) (12 ) (13 ) ( 9 ) (10 ) ( 8 ) ( 3 ) ( 5 ) ( 6 ) ( 4 ) ( 2 ) ( 1 )
+----- inorder(right) -----
+(15 ) (14 ) (13 ) (12 ) (11 ) (10 ) ( 9 ) ( 8 ) ( 7 ) ( 6 ) ( 5 ) ( 4 ) ( 3 ) ( 2 ) ( 1 )
+----- postorder(right) -----
+(15 ) (13 ) (12 ) (14 ) (10 ) ( 8 ) ( 9 ) (11 ) ( 6 ) ( 4 ) ( 5 ) ( 1 ) ( 2 ) ( 3 ) ( 7 )
+----- breadth(right) -----
+( 7 ) (11 ) ( 3 ) (14 ) ( 9 ) ( 5 ) ( 2 ) (15 ) (12 ) (10 ) ( 8 ) ( 6 ) ( 4 ) ( 1 ) (13 )
+----- left priority -----
+----- preorder -----
+( 7 ) ( 3 ) ( 2 ) ( 1 ) ( 5 ) ( 4 ) ( 6 ) (11 ) ( 9 ) ( 8 ) (10 ) (14 ) (12 ) (13 ) (15 )
+delete = ( 5 ) size = 14 : ( 7 ) ( 3 ) ( 2 ) ( 1 ) ( 6 ) ( 4 ) (11 ) ( 9 ) ( 8 ) (10 ) (14 ) (12 ) (13 ) (15 )
+delete = ( 2 ) size = 13 : ( 7 ) ( 3 ) ( 1 ) ( 6 ) ( 4 ) (11 ) ( 9 ) ( 8 ) (10 ) (14 ) (12 ) (13 ) (15 )
+delete = ( 3 ) size = 12 : ( 7 ) ( 4 ) ( 1 ) ( 6 ) (11 ) ( 9 ) ( 8 ) (10 ) (14 ) (12 ) (13 ) (15 )
+delete = ( 1 ) size = 11 : (11 ) ( 7 ) ( 4 ) ( 6 ) ( 9 ) ( 8 ) (10 ) (14 ) (12 ) (13 ) (15 )
+delete = ( 7 ) size = 10 : (11 ) ( 8 ) ( 4 ) ( 6 ) ( 9 ) (10 ) (14 ) (12 ) (13 ) (15 )
+delete = ( 8 ) size =  9 : (11 ) ( 9 ) ( 4 ) ( 6 ) (10 ) (14 ) (12 ) (13 ) (15 )
+delete = ( 6 ) size =  8 : (11 ) ( 9 ) ( 4 ) (10 ) (14 ) (12 ) (13 ) (15 )
+delete = ( 4 ) size =  7 : (11 ) ( 9 ) (10 ) (14 ) (12 ) (13 ) (15 )
+delete = ( 9 ) size =  6 : (12 ) (11 ) (10 ) (14 ) (13 ) (15 )
+delete = (10 ) size =  5 : (12 ) (11 ) (14 ) (13 ) (15 )
+delete = (12 ) size =  4 : (13 ) (11 ) (14 ) (15 )
+delete = (11 ) size =  3 : (14 ) (13 ) (15 )
+delete = (15 ) size =  2 : (14 ) (13 )
+delete = (14 ) size =  1 : (13 )
+delete = (13 ) size =  0 :
+----- empty -----
+```
diff --git a/src/tree.c b/src/tree.c
index 5543ef4..f0b2a89 100644
--- a/src/tree.c
+++ b/src/tree.c
@@ -10,6 +10,7 @@
  */
 #include "tree.h"
 #include "queue.h"
+#include "stack.h"
 
 #if RAVLTREE == 1
 // function declare
@@ -1947,6 +1948,7 @@ void tree_order(struct _tree* self, bool right_priority)
 
 void tree_avl_preorder(struct _tree* self, struct _tree_node* root)
 {
+#if 0
     assert(self != NULL);
     if(root == NULL)
     {
@@ -1977,6 +1979,47 @@ void tree_avl_preorder(struct _tree* self, struct _tree_node* root)
             tree_avl_preorder(self, root->left);
         }
     }
+#else
+    assert(self != NULL);
+    if(root == NULL)
+    {
+        return;
+    }
+    struct _tree_node* node = NULL;
+
+    stack_t stack = stack_new();
+    stack_init(stack, sizeof(struct _tree_node*));
+    stack->push(stack, &root);
+    while(!stack->empty(stack))
+    {
+        stack->pop(stack, &node);
+        if(!self->_right_priority)          // left priority
+        {
+            self->print_obj(node->obj);
+            if(node->right != NULL)
+            {
+                stack->push(stack, &node->right);
+            }
+            if(node->left != NULL)
+            {
+                stack->push(stack, &node->left);
+            }
+        }
+        else
+        {
+            self->print_obj(node->obj);
+            if(node->left != NULL)
+            {
+                stack->push(stack, &node->left);
+            }
+            if(node->right != NULL)
+            {
+                stack->push(stack, &node->right);
+            }
+        }
+    }
+    stack_free(stack);
+#endif
 }
 
 void tree_avl_inorder(struct _tree* self, struct _tree_node* root)