diff --git a/avl/avl.go b/avl/avl.go
index e67cc2f..53edc30 100644
--- a/avl/avl.go
+++ b/avl/avl.go
@@ -53,14 +53,14 @@ func (tree *Tree) Size() int {
 	return tree.size
 }
 
-func (tree *Tree) Remove(key interface{}) *Node {
+func (tree *Tree) Remove(key interface{}) (interface{}, bool) {
 
 	if n, ok := tree.GetNode(key); ok {
 
 		tree.size--
 		if tree.size == 0 {
 			tree.root = nil
-			return n
+			return n.value, true
 		}
 
 		left := getHeight(n.children[0])
@@ -70,7 +70,7 @@ func (tree *Tree) Remove(key interface{}) *Node {
 			p := n.parent
 			p.children[getRelationship(n)] = nil
 			tree.fixRemoveHeight(p)
-			return n
+			return n.value, true
 		}
 
 		var cur *Node
@@ -111,10 +111,10 @@ func (tree *Tree) Remove(key interface{}) *Node {
 			tree.fixRemoveHeight(cparent)
 		}
 
-		return cur
+		return cur.value, true
 	}
 
-	return nil
+	return nil, false
 }
 
 // Values 返回先序遍历的值
@@ -153,7 +153,6 @@ func (tree *Tree) GetRange(k1, k2 interface{}) (result []interface{}) {
 
 		result = make([]interface{}, 0, 16)
 
-		// iter := NewIterator(min)
 		tree.iter.SetNode(min)
 		iter := tree.iter
 		for iter.Next() {
@@ -180,7 +179,6 @@ func (tree *Tree) GetRange(k1, k2 interface{}) (result []interface{}) {
 
 		result = make([]interface{}, 0, 16)
 
-		// iter := NewIterator(max)
 		tree.iter.SetNode(max)
 		iter := tree.iter
 		for iter.Prev() {
@@ -232,7 +230,7 @@ func (tree *Tree) getArountNode(key interface{}) (result [3]*Node) {
 			n = n.children[1]
 			lastc = c
 		case 0:
-			// iter := NewIterator(n)
+
 			tree.iter.SetNode(n)
 			iter := tree.iter
 			iter.Prev()
@@ -292,10 +290,8 @@ func (tree *Tree) GetNode(value interface{}) (*Node, bool) {
 		case 1:
 			n = n.children[1]
 		case 0:
-			// iter := NewIterator(n)
 
 			tree.iter.SetNode(n)
-
 			iter := tree.iter
 			iter.Prev()
 			for iter.Prev() {
diff --git a/avl/avl_test.go b/avl/avl_test.go
index 86da345..bcd6423 100644
--- a/avl/avl_test.go
+++ b/avl/avl_test.go
@@ -5,7 +5,6 @@ import (
 	"encoding/gob"
 	"io/ioutil"
 	"log"
-	"os"
 	"testing"
 
 	"474420502.top/eson/structure/compare"
@@ -15,36 +14,6 @@ import (
 	"github.com/emirpasic/gods/trees/redblacktree"
 )
 
-const CompartorSize = 100
-const NumberMax = 600
-
-func Save(t *testing.T) {
-
-	f, err := os.OpenFile("../l.log", os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0666)
-	if err != nil {
-		log.Println(err)
-	}
-
-	//fmt.Println(userBytes)
-
-	var l []int
-	// m := make(map[int]int)
-	for i := 0; len(l) < CompartorSize; i++ {
-		v := randomdata.Number(0, NumberMax)
-		// if _, ok := m[v]; !ok {
-		// 	m[v] = v
-		l = append(l, v)
-		// }
-	}
-
-	var result bytes.Buffer
-	encoder := gob.NewEncoder(&result)
-	encoder.Encode(l)
-	lbytes := result.Bytes()
-	f.Write(lbytes)
-
-}
-
 func loadTestData() []int {
 	data, err := ioutil.ReadFile("../l.log")
 	if err != nil {
diff --git a/avldup/avldup.go b/avldup/avldup.go
index 8f811b1..bf22d0b 100644
--- a/avldup/avldup.go
+++ b/avldup/avldup.go
@@ -28,10 +28,12 @@ type Tree struct {
 	root    *Node
 	size    int
 	Compare compare.Compare
+
+	iter *Iterator
 }
 
 func New(Compare compare.Compare) *Tree {
-	return &Tree{Compare: Compare}
+	return &Tree{Compare: Compare, iter: NewIteratorWithCap(nil, 16)}
 }
 
 func (tree *Tree) String() string {
@@ -52,14 +54,14 @@ func (tree *Tree) Size() int {
 	return tree.size
 }
 
-func (tree *Tree) Remove(key interface{}) *Node {
+func (tree *Tree) Remove(key interface{}) (interface{}, bool) {
 
 	if n, ok := tree.GetNode(key); ok {
 
 		tree.size--
 		if tree.size == 0 {
 			tree.root = nil
-			return n
+			return n.value, true
 		}
 
 		left := getHeight(n.children[0])
@@ -69,7 +71,7 @@ func (tree *Tree) Remove(key interface{}) *Node {
 			p := n.parent
 			p.children[getRelationship(n)] = nil
 			tree.fixRemoveHeight(p)
-			return n
+			return n.value, true
 		}
 
 		var cur *Node
@@ -109,11 +111,10 @@ func (tree *Tree) Remove(key interface{}) *Node {
 		} else {
 			tree.fixRemoveHeight(cparent)
 		}
-
-		return cur
+		return cur.value, true
 	}
 
-	return nil
+	return nil, false
 }
 
 // Values 返回先序遍历的值
@@ -152,7 +153,8 @@ func (tree *Tree) GetRange(k1, k2 interface{}) (result []interface{}) {
 
 		result = make([]interface{}, 0, 16)
 
-		iter := NewIterator(min)
+		tree.iter.SetNode(min)
+		iter := tree.iter
 		for iter.Next() {
 			result = append(result, iter.Value())
 			if iter.cur == max {
@@ -177,7 +179,8 @@ func (tree *Tree) GetRange(k1, k2 interface{}) (result []interface{}) {
 
 		result = make([]interface{}, 0, 16)
 
-		iter := NewIterator(max)
+		tree.iter.SetNode(max)
+		iter := tree.iter
 		for iter.Prev() {
 			result = append(result, iter.Value())
 			if iter.cur == min {
@@ -239,21 +242,21 @@ func (tree *Tree) getArountNode(key interface{}) (result [3]*Node) {
 
 		if result[1] != nil {
 
-			result[0] = GetPrev(result[1], 1)
-			result[2] = GetNext(result[1], 1)
+			result[0] = tree.iter.GetPrev(result[1], 1)
+			result[2] = tree.iter.GetNext(result[1], 1)
 		} else {
 			result[0] = last
-			result[2] = GetNext(last, 1)
+			result[2] = tree.iter.GetNext(last, 1)
 		}
 
 	case -1:
 
 		if result[1] != nil {
-			result[0] = GetPrev(result[1], 1)
-			result[2] = GetNext(result[1], 1)
+			result[0] = tree.iter.GetPrev(result[1], 1)
+			result[2] = tree.iter.GetNext(result[1], 1)
 		} else {
 			result[2] = last
-			result[0] = GetPrev(last, 1)
+			result[0] = tree.iter.GetPrev(last, 1)
 		}
 
 	case 0:
@@ -261,8 +264,8 @@ func (tree *Tree) getArountNode(key interface{}) (result [3]*Node) {
 		if result[1] == nil {
 			return
 		}
-		result[0] = GetPrev(result[1], 1)
-		result[2] = GetNext(result[1], 1)
+		result[0] = tree.iter.GetPrev(result[1], 1)
+		result[2] = tree.iter.GetNext(result[1], 1)
 	}
 	return
 }
@@ -543,10 +546,6 @@ func (tree *Tree) rlrotate(cur *Node) {
 	cur.children[r] = mov
 	mov.parent = cur
 
-	// movparent.size = getChildrenSumSize(movparent) + 1
-	// mov.size = getChildrenSumSize(mov) + 1
-	// cur.size = getChildrenSumSize(cur) + 1
-
 	mov.height = getMaxChildrenHeight(mov) + 1
 	movparent.height = getMaxChildrenHeight(movparent) + 1
 	cur.height = getMaxChildrenHeight(cur) + 1
@@ -620,9 +619,6 @@ func (tree *Tree) rrotate(cur *Node) {
 	// 连接转移后的节点 由于mov只是与cur交换值,parent不变
 	cur.children[r] = mov
 
-	// mov.size = getChildrenSumSize(mov) + 1
-	// cur.size = getChildrenSumSize(cur) + 1
-
 	mov.height = getMaxChildrenHeight(mov) + 1
 	cur.height = getMaxChildrenHeight(cur) + 1
 }
@@ -659,9 +655,6 @@ func (tree *Tree) lrotateex(cur *Node) {
 
 	cur.children[r] = mov
 
-	// mov.size = getChildrenSumSize(mov) + 1
-	// cur.size = getChildrenSumSize(cur) + 1
-
 	mov.height = getMaxChildrenHeight(mov) + 1
 	cur.height = getMaxChildrenHeight(cur) + 1
 }
@@ -694,9 +687,6 @@ func (tree *Tree) lrotate(cur *Node) {
 
 	cur.children[r] = mov
 
-	// mov.size = getChildrenSumSize(mov) + 1
-	// cur.size = getChildrenSumSize(cur) + 1
-
 	mov.height = getMaxChildrenHeight(mov) + 1
 	cur.height = getMaxChildrenHeight(cur) + 1
 }
diff --git a/avldup/iterator.go b/avldup/iterator.go
index 303ce57..3fe6b63 100644
--- a/avldup/iterator.go
+++ b/avldup/iterator.go
@@ -9,6 +9,7 @@ type Iterator struct {
 	up     *Node
 	cur    *Node
 	tstack *lastack.Stack
+	// curnext *Node
 }
 
 func initIterator(avltree *Tree) *Iterator {
@@ -23,6 +24,18 @@ func NewIterator(n *Node) *Iterator {
 	return iter
 }
 
+func NewIteratorWithCap(n *Node, cap int) *Iterator {
+	iter := &Iterator{tstack: lastack.NewWithCap(cap)}
+	iter.up = n
+	return iter
+}
+
+func (iter *Iterator) SetNode(n *Node) {
+	iter.up = n
+	iter.dir = 0
+	iter.tstack.Clear()
+}
+
 func (iter *Iterator) Value() interface{} {
 	return iter.cur.value
 }
@@ -45,9 +58,10 @@ func (iter *Iterator) Right() bool {
 	return false
 }
 
-func GetNext(cur *Node, idx int) *Node {
+func (iter *Iterator) GetNext(cur *Node, idx int) *Node {
 
-	iter := NewIterator(cur)
+	// iter := NewIterator(cur)
+	iter.SetNode(cur)
 	iter.curPushNextStack(iter.up)
 	iter.up = iter.getNextUp(iter.up)
 
@@ -102,9 +116,10 @@ func (iter *Iterator) Next() (result bool) {
 
 	return false
 }
-func GetPrev(cur *Node, idx int) *Node {
+func (iter *Iterator) GetPrev(cur *Node, idx int) *Node {
 
-	iter := NewIterator(cur)
+	// iter := NewIterator(cur)
+	iter.SetNode(cur)
 	iter.curPushPrevStack(iter.up)
 	iter.up = iter.getPrevUp(iter.up)
 
diff --git a/avlkey/avlkey.go b/avlkey/avlkey.go
index 7ae1f41..1489c83 100644
--- a/avlkey/avlkey.go
+++ b/avlkey/avlkey.go
@@ -28,10 +28,12 @@ type Tree struct {
 	root    *Node
 	size    int
 	Compare compare.Compare
+
+	iter *Iterator
 }
 
 func New(Compare compare.Compare) *Tree {
-	return &Tree{Compare: Compare}
+	return &Tree{Compare: Compare, iter: NewIteratorWithCap(nil, 16)}
 }
 
 func (tree *Tree) String() string {
@@ -52,14 +54,14 @@ func (tree *Tree) Size() int {
 	return tree.size
 }
 
-func (tree *Tree) Remove(key interface{}) *Node {
+func (tree *Tree) Remove(key interface{}) (interface{}, bool) {
 
 	if n, ok := tree.GetNode(key); ok {
 
 		tree.size--
 		if tree.size == 0 {
 			tree.root = nil
-			return n
+			return n.value, true
 		}
 
 		left := getHeight(n.children[0])
@@ -69,7 +71,7 @@ func (tree *Tree) Remove(key interface{}) *Node {
 			p := n.parent
 			p.children[getRelationship(n)] = nil
 			tree.fixRemoveHeight(p)
-			return n
+			return n.value, true
 		}
 
 		var cur *Node
@@ -110,10 +112,10 @@ func (tree *Tree) Remove(key interface{}) *Node {
 			tree.fixRemoveHeight(cparent)
 		}
 
-		return cur
+		return cur.value, true
 	}
 
-	return nil
+	return nil, false
 }
 
 // Values 返回先序遍历的值
@@ -152,7 +154,8 @@ func (tree *Tree) GetRange(k1, k2 interface{}) (result []interface{}) {
 
 		result = make([]interface{}, 0, 16)
 
-		iter := NewIterator(min)
+		tree.iter.SetNode(min)
+		iter := tree.iter
 		for iter.Next() {
 			result = append(result, iter.Value())
 			if iter.cur == max {
@@ -177,7 +180,8 @@ func (tree *Tree) GetRange(k1, k2 interface{}) (result []interface{}) {
 
 		result = make([]interface{}, 0, 16)
 
-		iter := NewIterator(max)
+		tree.iter.SetNode(max)
+		iter := tree.iter
 		for iter.Prev() {
 			result = append(result, iter.Value())
 			if iter.cur == min {
@@ -227,7 +231,9 @@ func (tree *Tree) getArountNode(key interface{}) (result [3]*Node) {
 			n = n.children[1]
 			lastc = c
 		case 0:
-			iter := NewIterator(n)
+
+			tree.iter.SetNode(n)
+			iter := tree.iter
 			iter.Prev()
 			for iter.Prev() {
 				if tree.Compare(iter.cur.value, n.value) == 0 {
@@ -248,21 +254,21 @@ func (tree *Tree) getArountNode(key interface{}) (result [3]*Node) {
 
 		if result[1] != nil {
 
-			result[0] = GetPrev(result[1], 1)
-			result[2] = GetNext(result[1], 1)
+			result[0] = tree.iter.GetPrev(result[1], 1)
+			result[2] = tree.iter.GetNext(result[1], 1)
 		} else {
 			result[0] = last
-			result[2] = GetNext(last, 1)
+			result[2] = tree.iter.GetNext(last, 1)
 		}
 
 	case -1:
 
 		if result[1] != nil {
-			result[0] = GetPrev(result[1], 1)
-			result[2] = GetNext(result[1], 1)
+			result[0] = tree.iter.GetPrev(result[1], 1)
+			result[2] = tree.iter.GetNext(result[1], 1)
 		} else {
 			result[2] = last
-			result[0] = GetPrev(last, 1)
+			result[0] = tree.iter.GetPrev(last, 1)
 		}
 
 	case 0:
@@ -270,8 +276,8 @@ func (tree *Tree) getArountNode(key interface{}) (result [3]*Node) {
 		if result[1] == nil {
 			return
 		}
-		result[0] = GetPrev(result[1], 1)
-		result[2] = GetNext(result[1], 1)
+		result[0] = tree.iter.GetPrev(result[1], 1)
+		result[2] = tree.iter.GetNext(result[1], 1)
 	}
 	return
 }
@@ -285,7 +291,8 @@ func (tree *Tree) GetNode(key interface{}) (*Node, bool) {
 		case 1:
 			n = n.children[1]
 		case 0:
-			iter := NewIterator(n)
+			tree.iter.SetNode(n)
+			iter := tree.iter
 			iter.Prev()
 			for iter.Prev() {
 				if tree.Compare(iter.cur.key, n.key) == 0 {
diff --git a/avlkey/avlkey_test.go b/avlkey/avlkey_test.go
index 8581387..ad9da8f 100644
--- a/avlkey/avlkey_test.go
+++ b/avlkey/avlkey_test.go
@@ -16,36 +16,6 @@ import (
 	"github.com/emirpasic/gods/utils"
 )
 
-const CompartorSize = 100
-const NumberMax = 600
-
-func Save(t *testing.T) {
-
-	f, err := os.OpenFile("../l.log", os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0666)
-	if err != nil {
-		log.Println(err)
-	}
-
-	//fmt.Println(userBytes)
-
-	var l []int
-	// m := make(map[int]int)
-	for i := 0; len(l) < CompartorSize; i++ {
-		v := randomdata.Number(0, NumberMax)
-		// if _, ok := m[v]; !ok {
-		// 	m[v] = v
-		l = append(l, v)
-		// }
-	}
-
-	var result bytes.Buffer
-	encoder := gob.NewEncoder(&result)
-	encoder.Encode(l)
-	lbytes := result.Bytes()
-	f.Write(lbytes)
-
-}
-
 func loadTestData() []int {
 	data, err := ioutil.ReadFile("../l.log")
 	if err != nil {
diff --git a/avlkey/iterator.go b/avlkey/iterator.go
index b8173b2..555efa8 100644
--- a/avlkey/iterator.go
+++ b/avlkey/iterator.go
@@ -24,6 +24,18 @@ func NewIterator(n *Node) *Iterator {
 	return iter
 }
 
+func NewIteratorWithCap(n *Node, cap int) *Iterator {
+	iter := &Iterator{tstack: lastack.NewWithCap(cap)}
+	iter.up = n
+	return iter
+}
+
+func (iter *Iterator) SetNode(n *Node) {
+	iter.up = n
+	iter.dir = 0
+	iter.tstack.Clear()
+}
+
 func (iter *Iterator) Value() interface{} {
 	return iter.cur.value
 }
@@ -46,9 +58,10 @@ func (iter *Iterator) Right() bool {
 	return false
 }
 
-func GetNext(cur *Node, idx int) *Node {
+func (iter *Iterator) GetNext(cur *Node, idx int) *Node {
 
-	iter := NewIterator(cur)
+	// iter := NewIterator(cur)
+	iter.SetNode(cur)
 	iter.curPushNextStack(iter.up)
 	iter.up = iter.getNextUp(iter.up)
 
@@ -103,9 +116,10 @@ func (iter *Iterator) Next() (result bool) {
 
 	return false
 }
-func GetPrev(cur *Node, idx int) *Node {
+func (iter *Iterator) GetPrev(cur *Node, idx int) *Node {
 
-	iter := NewIterator(cur)
+	// iter := NewIterator(cur)
+	iter.SetNode(cur)
 	iter.curPushPrevStack(iter.up)
 	iter.up = iter.getPrevUp(iter.up)
 
diff --git a/avlkeydup/avlkeydup.go b/avlkeydup/avlkeydup.go
index 7c0a857..c113f56 100644
--- a/avlkeydup/avlkeydup.go
+++ b/avlkeydup/avlkeydup.go
@@ -28,10 +28,12 @@ type Tree struct {
 	root    *Node
 	size    int
 	Compare compare.Compare
+
+	iter *Iterator
 }
 
 func New(Compare compare.Compare) *Tree {
-	return &Tree{Compare: Compare}
+	return &Tree{Compare: Compare, iter: NewIteratorWithCap(nil, 16)}
 }
 
 func (tree *Tree) String() string {
@@ -52,14 +54,14 @@ func (tree *Tree) Size() int {
 	return tree.size
 }
 
-func (tree *Tree) Remove(key interface{}) *Node {
+func (tree *Tree) Remove(key interface{}) (interface{}, bool) {
 
 	if n, ok := tree.GetNode(key); ok {
 
 		tree.size--
 		if tree.size == 0 {
 			tree.root = nil
-			return n
+			return n.value, true
 		}
 
 		left := getHeight(n.children[0])
@@ -69,7 +71,7 @@ func (tree *Tree) Remove(key interface{}) *Node {
 			p := n.parent
 			p.children[getRelationship(n)] = nil
 			tree.fixRemoveHeight(p)
-			return n
+			return n.value, true
 		}
 
 		var cur *Node
@@ -110,10 +112,10 @@ func (tree *Tree) Remove(key interface{}) *Node {
 			tree.fixRemoveHeight(cparent)
 		}
 
-		return cur
+		return cur.value, true
 	}
 
-	return nil
+	return nil, false
 }
 
 // Values 返回先序遍历的值
@@ -152,7 +154,8 @@ func (tree *Tree) GetRange(k1, k2 interface{}) (result []interface{}) {
 
 		result = make([]interface{}, 0, 16)
 
-		iter := NewIterator(min)
+		tree.iter.SetNode(min)
+		iter := tree.iter
 		for iter.Next() {
 			result = append(result, iter.Value())
 			if iter.cur == max {
@@ -177,7 +180,8 @@ func (tree *Tree) GetRange(k1, k2 interface{}) (result []interface{}) {
 
 		result = make([]interface{}, 0, 16)
 
-		iter := NewIterator(max)
+		tree.iter.SetNode(max)
+		iter := tree.iter
 		for iter.Prev() {
 			result = append(result, iter.Value())
 			if iter.cur == min {
@@ -227,7 +231,9 @@ func (tree *Tree) getArountNode(key interface{}) (result [3]*Node) {
 			n = n.children[1]
 			lastc = c
 		case 0:
-			iter := NewIterator(n)
+
+			tree.iter.SetNode(n)
+			iter := tree.iter
 			iter.Prev()
 			for iter.Prev() {
 				if tree.Compare(iter.cur.value, n.value) == 0 {
@@ -248,21 +254,21 @@ func (tree *Tree) getArountNode(key interface{}) (result [3]*Node) {
 
 		if result[1] != nil {
 
-			result[0] = GetPrev(result[1], 1)
-			result[2] = GetNext(result[1], 1)
+			result[0] = tree.iter.GetPrev(result[1], 1)
+			result[2] = tree.iter.GetNext(result[1], 1)
 		} else {
 			result[0] = last
-			result[2] = GetNext(last, 1)
+			result[2] = tree.iter.GetNext(last, 1)
 		}
 
 	case -1:
 
 		if result[1] != nil {
-			result[0] = GetPrev(result[1], 1)
-			result[2] = GetNext(result[1], 1)
+			result[0] = tree.iter.GetPrev(result[1], 1)
+			result[2] = tree.iter.GetNext(result[1], 1)
 		} else {
 			result[2] = last
-			result[0] = GetPrev(last, 1)
+			result[0] = tree.iter.GetPrev(last, 1)
 		}
 
 	case 0:
@@ -270,8 +276,8 @@ func (tree *Tree) getArountNode(key interface{}) (result [3]*Node) {
 		if result[1] == nil {
 			return
 		}
-		result[0] = GetPrev(result[1], 1)
-		result[2] = GetNext(result[1], 1)
+		result[0] = tree.iter.GetPrev(result[1], 1)
+		result[2] = tree.iter.GetNext(result[1], 1)
 	}
 	return
 }
@@ -285,7 +291,9 @@ func (tree *Tree) GetNode(key interface{}) (*Node, bool) {
 		case 1:
 			n = n.children[1]
 		case 0:
-			iter := NewIterator(n)
+
+			tree.iter.SetNode(n)
+			iter := tree.iter
 			iter.Prev()
 			for iter.Prev() {
 				if tree.Compare(iter.cur.key, n.key) == 0 {
diff --git a/avlkeydup/iterator.go b/avlkeydup/iterator.go
index ac617a1..ffa1a24 100644
--- a/avlkeydup/iterator.go
+++ b/avlkeydup/iterator.go
@@ -24,6 +24,18 @@ func NewIterator(n *Node) *Iterator {
 	return iter
 }
 
+func NewIteratorWithCap(n *Node, cap int) *Iterator {
+	iter := &Iterator{tstack: lastack.NewWithCap(cap)}
+	iter.up = n
+	return iter
+}
+
+func (iter *Iterator) SetNode(n *Node) {
+	iter.up = n
+	iter.dir = 0
+	iter.tstack.Clear()
+}
+
 func (iter *Iterator) Value() interface{} {
 	return iter.cur.value
 }
@@ -46,9 +58,10 @@ func (iter *Iterator) Right() bool {
 	return false
 }
 
-func GetNext(cur *Node, idx int) *Node {
+func (iter *Iterator) GetNext(cur *Node, idx int) *Node {
 
-	iter := NewIterator(cur)
+	// iter := NewIterator(cur)
+	iter.SetNode(cur)
 	iter.curPushNextStack(iter.up)
 	iter.up = iter.getNextUp(iter.up)
 
@@ -103,9 +116,10 @@ func (iter *Iterator) Next() (result bool) {
 
 	return false
 }
-func GetPrev(cur *Node, idx int) *Node {
+func (iter *Iterator) GetPrev(cur *Node, idx int) *Node {
 
-	iter := NewIterator(cur)
+	// iter := NewIterator(cur)
+	iter.SetNode(cur)
 	iter.curPushPrevStack(iter.up)
 	iter.up = iter.getPrevUp(iter.up)
 
diff --git a/interface.go b/interface.go
index a80b419..6fe4564 100644
--- a/interface.go
+++ b/interface.go
@@ -1,9 +1 @@
 package structure
-
-type IteratorNext interface {
-	Next() bool
-}
-
-type IteratorPrev interface {
-	Prev() bool
-}
diff --git a/priority_queue/priority_queue.go b/priority_queue/priority_queue.go
index 49fa0d1..18bfd14 100644
--- a/priority_queue/priority_queue.go
+++ b/priority_queue/priority_queue.go
@@ -67,11 +67,11 @@ func (pq *PriorityQueue) GetRange(k1, k2 interface{}) []interface{} {
 	return pq.queue.GetRange(k1, k2)
 }
 
-func (pq *PriorityQueue) RemoveIndex(idx int) (*Node, bool) {
+func (pq *PriorityQueue) RemoveIndex(idx int) (interface{}, bool) {
 	return pq.queue.RemoveIndex(idx)
 }
 
-func (pq *PriorityQueue) Remove(key interface{}) (*Node, bool) {
+func (pq *PriorityQueue) Remove(key interface{}) (interface{}, bool) {
 	return pq.queue.Remove(key)
 }
 
diff --git a/priority_queue/vbt.go b/priority_queue/vbt.go
index df8c88d..fab0650 100644
--- a/priority_queue/vbt.go
+++ b/priority_queue/vbt.go
@@ -156,11 +156,11 @@ func (tree *vbTree) IndexRange(idx1, idx2 int) (result []interface{}, ok bool) {
 	return nil, false
 }
 
-func (tree *vbTree) RemoveIndex(idx int) (*Node, bool) {
+func (tree *vbTree) RemoveIndex(idx int) (interface{}, bool) {
 	n := tree.indexNode(idx)
 	if n != nil {
 		tree.removeNode(n)
-		return n, true
+		return n.value, true
 	}
 	return nil, false
 }
@@ -229,11 +229,11 @@ func (tree *vbTree) removeNode(n *Node) {
 	return
 }
 
-func (tree *vbTree) Remove(key interface{}) (*Node, bool) {
+func (tree *vbTree) Remove(key interface{}) (interface{}, bool) {
 
 	if n, ok := tree.GetNode(key); ok {
 		tree.removeNode(n)
-		return n, true
+		return n.value, true
 	}
 	// return nil
 	return nil, false
diff --git a/priority_queue/vbt_test.go b/priority_queue/vbt_test.go
index d00734e..f366461 100644
--- a/priority_queue/vbt_test.go
+++ b/priority_queue/vbt_test.go
@@ -5,7 +5,6 @@ import (
 	"encoding/gob"
 	"io/ioutil"
 	"log"
-	"os"
 	"testing"
 
 	"474420502.top/eson/structure/compare"
@@ -17,38 +16,6 @@ import (
 	"github.com/emirpasic/gods/trees/redblacktree"
 )
 
-const CompareSize = 1000000
-const NumberMax = 50000000
-
-func Save(t *testing.T) {
-
-	f, err := os.OpenFile("../l.log", os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0666)
-	if err != nil {
-		log.Println(err)
-	}
-	var l []int
-	// for i := 0; len(l) < 1000; i++ {
-	// 	v := randomdata.Number(0, 65535)
-	// 	l = append(l, v)
-	// }
-
-	m := make(map[int]int)
-	for i := 0; len(l) < CompareSize; i++ {
-		v := randomdata.Number(0, NumberMax)
-		if _, ok := m[v]; !ok {
-			m[v] = v
-			l = append(l, v)
-		}
-	}
-
-	var result bytes.Buffer
-	encoder := gob.NewEncoder(&result)
-	encoder.Encode(l)
-	lbytes := result.Bytes()
-	f.Write(lbytes)
-
-}
-
 func loadTestData() []int {
 	data, err := ioutil.ReadFile("../l.log")
 	if err != nil {
diff --git a/test.sh b/test.sh
new file mode 100644
index 0000000..c3874fe
--- /dev/null
+++ b/test.sh
@@ -0,0 +1 @@
+cd avl ; go test -v
diff --git a/vbt/vbt.go b/vbt/vbt.go
index 4dbef38..4ce84c7 100644
--- a/vbt/vbt.go
+++ b/vbt/vbt.go
@@ -154,11 +154,11 @@ func (tree *Tree) IndexRange(idx1, idx2 int) (result []interface{}, ok bool) { /
 	return nil, false
 }
 
-func (tree *Tree) RemoveIndex(idx int) (*Node, bool) {
+func (tree *Tree) RemoveIndex(idx int) (interface{}, bool) {
 	n := tree.indexNode(idx)
 	if n != nil {
 		tree.removeNode(n)
-		return n, true
+		return n.value, true
 	}
 	return nil, false
 }
@@ -221,11 +221,11 @@ func (tree *Tree) removeNode(n *Node) {
 	return
 }
 
-func (tree *Tree) Remove(key interface{}) (*Node, bool) {
+func (tree *Tree) Remove(key interface{}) (interface{}, bool) {
 
 	if n, ok := tree.GetNode(key); ok {
 		tree.removeNode(n)
-		return n, true
+		return n.value, true
 	}
 	// return nil
 	return nil, false
diff --git a/vbt/vbt_test.go b/vbt/vbt_test.go
index 1c59614..751a8ad 100644
--- a/vbt/vbt_test.go
+++ b/vbt/vbt_test.go
@@ -5,7 +5,6 @@ import (
 	"encoding/gob"
 	"io/ioutil"
 	"log"
-	"os"
 	"testing"
 
 	"474420502.top/eson/structure/compare"
@@ -17,38 +16,6 @@ import (
 	"github.com/emirpasic/gods/trees/redblacktree"
 )
 
-const CompareSize = 1000000
-const NumberMax = 50000000
-
-func TestSave(t *testing.T) {
-
-	f, err := os.OpenFile("../l.log", os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0666)
-	if err != nil {
-		log.Println(err)
-	}
-	var l []int
-	// for i := 0; len(l) < 1000; i++ {
-	// 	v := randomdata.Number(0, 65535)
-	// 	l = append(l, v)
-	// }
-
-	m := make(map[int]int)
-	for i := 0; len(l) < CompareSize; i++ {
-		v := randomdata.Number(0, NumberMax)
-		if _, ok := m[v]; !ok {
-			m[v] = v
-			l = append(l, v)
-		}
-	}
-
-	var result bytes.Buffer
-	encoder := gob.NewEncoder(&result)
-	encoder.Encode(l)
-	lbytes := result.Bytes()
-	f.Write(lbytes)
-
-}
-
 func loadTestData() []int {
 	data, err := ioutil.ReadFile("../l.log")
 	if err != nil {
diff --git a/vbtkey/vbtkey.go b/vbtkey/vbtkey.go
index 78501ee..18da20b 100644
--- a/vbtkey/vbtkey.go
+++ b/vbtkey/vbtkey.go
@@ -155,11 +155,11 @@ func (tree *Tree) IndexRange(idx1, idx2 int) (result []interface{}, ok bool) { /
 	return nil, false
 }
 
-func (tree *Tree) RemoveIndex(idx int) (*Node, bool) {
+func (tree *Tree) RemoveIndex(idx int) (interface{}, bool) {
 	n := tree.indexNode(idx)
 	if n != nil {
 		tree.removeNode(n)
-		return n, true
+		return n.value, true
 	}
 	return nil, false
 }
@@ -222,11 +222,11 @@ func (tree *Tree) removeNode(n *Node) {
 	return
 }
 
-func (tree *Tree) Remove(key interface{}) (*Node, bool) {
+func (tree *Tree) Remove(key interface{}) (interface{}, bool) {
 
 	if n, ok := tree.GetNode(key); ok {
 		tree.removeNode(n)
-		return n, true
+		return n.value, true
 	}
 	// return nil
 	return nil, false
diff --git a/vbtkey/vbtkey_test.go b/vbtkey/vbtkey_test.go
index a4379d2..fda305e 100644
--- a/vbtkey/vbtkey_test.go
+++ b/vbtkey/vbtkey_test.go
@@ -5,7 +5,6 @@ import (
 	"encoding/gob"
 	"io/ioutil"
 	"log"
-	"os"
 	"testing"
 
 	"474420502.top/eson/structure/compare"
@@ -17,38 +16,6 @@ import (
 	"github.com/emirpasic/gods/trees/redblacktree"
 )
 
-const CompareSize = 1000000
-const NumberMax = 50000000
-
-func TestSave(t *testing.T) {
-
-	f, err := os.OpenFile("../l.log", os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0666)
-	if err != nil {
-		log.Println(err)
-	}
-	var l []int
-	// for i := 0; len(l) < 1000; i++ {
-	// 	v := randomdata.Number(0, 65535)
-	// 	l = append(l, v)
-	// }
-
-	//m := make(map[int]int)
-	for i := 0; len(l) < CompareSize; i++ {
-		v := randomdata.Number(0, NumberMax)
-		// if _, ok := m[v]; !ok {
-		// 	m[v] = v
-		l = append(l, v)
-		// }
-	}
-
-	var result bytes.Buffer
-	encoder := gob.NewEncoder(&result)
-	encoder.Encode(l)
-	lbytes := result.Bytes()
-	f.Write(lbytes)
-
-}
-
 func loadTestData() []int {
 	data, err := ioutil.ReadFile("../l.log")
 	if err != nil {