完善了avl 并且修改了 升序为和核心 TODO: 需要修改vbt iterator 和 其他

avl/avl.go

@@ -34,31 +34,31 @@ func New(compare compare.Compare) *Tree {
 	return &Tree{compare: compare}
 }
 
-func (avl *Tree) String() string {
+func (tree *Tree) String() string {
-	if avl.size == 0 {
+	if tree.size == 0 {
 		return ""
 	}
 	str := "AVLTree\n"
-	output(avl.root, "", true, &str)
+	output(tree.root, "", true, &str)
 
 	return str
 }
 
-func (avl *Tree) Iterator() *Iterator {
+func (tree *Tree) Iterator() *Iterator {
-	return initIterator(avl)
+	return initIterator(tree)
 }
 
-func (avl *Tree) Size() int {
+func (tree *Tree) Size() int {
-	return avl.size
+	return tree.size
 }
 
-func (avl *Tree) Remove(key interface{}) *Node {
+func (tree *Tree) Remove(key interface{}) *Node {
 
-	if n, ok := avl.GetNode(key); ok {
+	if n, ok := tree.GetNode(key); ok {
 
-		avl.size--
+		tree.size--
-		if avl.size == 0 {
+		if tree.size == 0 {
-			avl.root = nil
+			tree.root = nil
 			return n
 		}
 
@@ -68,7 +68,7 @@ func (avl *Tree) Remove(key interface{}) *Node {
 		if left == -1 && right == -1 {
 			p := n.parent
 			p.children[getRelationship(n)] = nil
-			avl.fixRemoveHeight(p)
+			tree.fixRemoveHeight(p)
 			return n
 		}
 
@@ -105,9 +105,9 @@ func (avl *Tree) Remove(key interface{}) *Node {
 
 		// 考虑到刚好替换的节点是 被替换节点的孩子节点的时候, 从自身修复高度
 		if cparent == n {
-			avl.fixRemoveHeight(n)
+			tree.fixRemoveHeight(n)
 		} else {
-			avl.fixRemoveHeight(cparent)
+			tree.fixRemoveHeight(cparent)
 		}
 
 		return cur
@@ -153,7 +153,7 @@ func (tree *Tree) GetRange(k1, k2 interface{}) (result []interface{}) {
 		result = make([]interface{}, 0, 16)
 
 		iter := NewIterator(min)
-		for iter.Prev() {
+		for iter.Next() {
 			result = append(result, iter.Value())
 			if iter.cur == max {
 				break
@@ -178,7 +178,7 @@ func (tree *Tree) GetRange(k1, k2 interface{}) (result []interface{}) {
 		result = make([]interface{}, 0, 16)
 
 		iter := NewIterator(max)
-		for iter.Next() {
+		for iter.Prev() {
 			result = append(result, iter.Value())
 			if iter.cur == min {
 				break
@@ -194,8 +194,8 @@ func (tree *Tree) GetRange(k1, k2 interface{}) (result []interface{}) {
 	return
 }
 
-func (avl *Tree) Get(key interface{}) (interface{}, bool) {
+func (tree *Tree) Get(key interface{}) (interface{}, bool) {
-	n, ok := avl.GetNode(key)
+	n, ok := tree.GetNode(key)
 	if ok {
 		return n.value, true
 	}
@@ -227,6 +227,15 @@ func (tree *Tree) getArountNode(key interface{}) (result [3]*Node) {
 			n = n.children[1]
 			lastc = c
 		case 0:
+			iter := NewIterator(n)
+			iter.Prev()
+			for iter.Prev() {
+				if tree.compare(iter.cur.value, n.value) == 0 {
+					n = iter.cur
+				} else {
+					break
+				}
+			}
 			result[1] = n
 			n = nil
 		default:
@@ -236,146 +245,83 @@ func (tree *Tree) getArountNode(key interface{}) (result [3]*Node) {
 
 	switch lastc {
 	case 1:
-		const il = 0
-		const ir = 1
 
-		if result[1] == nil {
+		if result[1] != nil {
-			result[0] = last
-
-			parent := last
-			for ; parent != nil && parent.parent != nil; parent = parent.parent {
-				child := getRelationship(parent)
-				if child == (-lastc+2)/2 { // child 与 compare 后左右的关系
-					result[2] = parent.parent
-					break
-				}
-			}
 
+			result[0] = GetPrev(result[1], 1)
+			result[2] = GetNext(result[1], 1)
 		} else {
-			l := result[1].children[il]
+			result[0] = last
-			r := result[1].children[ir]
+			result[2] = GetNext(last, 1)
-
-			if l == nil {
-				result[0] = result[1].parent
-			} else {
-				for l.children[ir] != nil {
-					l = l.children[ir]
-				}
-				result[0] = l
-			}
-
-			if r == nil {
-
-				parent := result[1].parent
-				for ; parent != nil && parent.parent != nil; parent = parent.parent {
-					child := getRelationship(parent)
-					if child == (-lastc+2)/2 { // child 与 compare 后左右的关系
-						result[2] = parent.parent
-						break
-					}
-				}
-
-			} else {
-				for r.children[il] != nil {
-					r = r.children[il]
-				}
-				result[2] = r
-			}
 		}
 
 	case -1:
 
-		const il = 1
+		if result[1] != nil {
-		const ir = 0
+			result[0] = GetPrev(result[1], 1)
-
+			result[2] = GetNext(result[1], 1)
-		if result[1] == nil {
-			result[2] = last
-
-			parent := last
-			for ; parent != nil && parent.parent != nil; parent = parent.parent {
-				child := getRelationship(parent)
-				if child == (-lastc+2)/2 { // child 与 compare 后左右的关系
-					result[0] = parent.parent
-					break
-				}
-			}
-
 		} else {
-
+			result[2] = last
-			l := result[1].children[il]
+			result[0] = GetPrev(last, 1)
-			r := result[1].children[ir]
-
-			if l == nil {
-				result[2] = result[1].parent
-			} else {
-				for l.children[ir] != nil {
-					l = l.children[ir]
-				}
-				result[2] = l
-			}
-
-			if r == nil {
-
-				parent := result[1].parent
-				for ; parent != nil && parent.parent != nil; parent = parent.parent {
-					child := getRelationship(parent)
-					if child == (-lastc+2)/2 { // child 与 compare 后左右的关系
-						result[0] = parent.parent
-						break
-					}
-				}
-
-			} else {
-
-				for r.children[il] != nil {
-					r = r.children[il]
-				}
-				result[0] = r
-
-			}
 		}
-	case 0:
 
-		const il = 0
+	case 0:
-		const ir = 1
 
 		if result[1] == nil {
 			return
 		}
+		result[0] = GetPrev(result[1], 1)
+		result[2] = GetNext(result[1], 1)
 
-		l := result[1].children[il]
+		// const il = 0
-		r := result[1].children[ir]
+		// const ir = 1
 
-		if l == nil {
+		// if result[1] == nil {
-			result[0] = nil
+		// 	return
-		} else {
+		// }
-			for l.children[ir] != nil {
-				l = l.children[ir]
-			}
-			result[0] = l
-		}
 
-		if r == nil {
+		// l := result[1].children[il]
-			result[2] = nil
+		// r := result[1].children[ir]
-		} else {
+
-			for r.children[il] != nil {
+		// if l == nil {
-				r = r.children[il]
+		// 	result[0] = nil
-			}
+		// } else {
-			result[2] = r
+		// 	for l.children[ir] != nil {
-		}
+		// 		l = l.children[ir]
+		// 	}
+		// 	result[0] = l
+		// }
+
+		// if r == nil {
+		// 	result[2] = nil
+		// } else {
+		// 	for r.children[il] != nil {
+		// 		r = r.children[il]
+		// 	}
+		// 	result[2] = r
+		// }
 	}
 	return
 }
 
-func (avl *Tree) GetNode(value interface{}) (*Node, bool) {
+func (tree *Tree) GetNode(value interface{}) (*Node, bool) {
 
-	for n := avl.root; n != nil; {
+	for n := tree.root; n != nil; {
-		switch c := avl.compare(value, n.value); c {
+		switch c := tree.compare(value, n.value); c {
 		case -1:
 			n = n.children[0]
 		case 1:
 			n = n.children[1]
 		case 0:
+			iter := NewIterator(n)
+			iter.Prev()
+			for iter.Prev() {
+				if tree.compare(iter.cur.value, n.value) == 0 {
+					n = iter.cur
+				} else {
+					break
+				}
+			}
 			return n, true
 		default:
 			panic("Get compare only is allowed in -1, 0, 1")
@@ -384,15 +330,15 @@ func (avl *Tree) GetNode(value interface{}) (*Node, bool) {
 	return nil, false
 }
 
-func (avl *Tree) Put(value interface{}) {
+func (tree *Tree) Put(value interface{}) {
-	avl.size++
+	tree.size++
 	node := &Node{value: value}
-	if avl.size == 1 {
+	if tree.size == 1 {
-		avl.root = node
+		tree.root = node
 		return
 	}
 
-	cur := avl.root
+	cur := tree.root
 	parent := cur.parent
 	child := -1
 
@@ -402,13 +348,13 @@ func (avl *Tree) Put(value interface{}) {
 			parent.children[child] = node
 			node.parent = parent
 			if node.parent.height == 0 {
-				avl.fixPutHeight(node.parent)
+				tree.fixPutHeight(node.parent)
 			}
 			return
 		}
 
 		parent = cur
-		c := avl.compare(value, cur.value)
+		c := tree.compare(value, cur.value)
 		child = (c + 2) / 2
 		cur = cur.children[child]
 	}
@@ -559,7 +505,7 @@ func (tree *Tree) Traversal(every func(v interface{}) bool, traversalMethod ...i
 	}
 }
 
-func (avl *Tree) lrrotate(cur *Node) {
+func (tree *Tree) lrrotate(cur *Node) {
 
 	const l = 1
 	const r = 0
@@ -603,7 +549,7 @@ func (avl *Tree) lrrotate(cur *Node) {
 	cur.height = getMaxChildrenHeight(cur) + 1
 }
 
-func (avl *Tree) rlrotate(cur *Node) {
+func (tree *Tree) rlrotate(cur *Node) {
 
 	const l = 0
 	const r = 1
@@ -645,7 +591,7 @@ func (avl *Tree) rlrotate(cur *Node) {
 	cur.height = getMaxChildrenHeight(cur) + 1
 }
 
-func (avl *Tree) rrotateex(cur *Node) {
+func (tree *Tree) rrotateex(cur *Node) {
 
 	const l = 0
 	const r = 1
@@ -683,7 +629,7 @@ func (avl *Tree) rrotateex(cur *Node) {
 	cur.height = getMaxChildrenHeight(cur) + 1
 }
 
-func (avl *Tree) rrotate(cur *Node) {
+func (tree *Tree) rrotate(cur *Node) {
 
 	const l = 0
 	const r = 1
@@ -720,7 +666,7 @@ func (avl *Tree) rrotate(cur *Node) {
 	cur.height = getMaxChildrenHeight(cur) + 1
 }
 
-func (avl *Tree) lrotateex(cur *Node) {
+func (tree *Tree) lrotateex(cur *Node) {
 
 	const l = 1
 	const r = 0
@@ -759,7 +705,7 @@ func (avl *Tree) lrotateex(cur *Node) {
 	cur.height = getMaxChildrenHeight(cur) + 1
 }
 
-func (avl *Tree) lrotate(cur *Node) {
+func (tree *Tree) lrotate(cur *Node) {
 
 	const l = 1
 	const r = 0
@@ -822,7 +768,7 @@ func getHeight(cur *Node) int {
 	return cur.height
 }
 
-func (avl *Tree) fixRemoveHeight(cur *Node) {
+func (tree *Tree) fixRemoveHeight(cur *Node) {
 	for {
 
 		lefth, rigthh, lrmax := getMaxAndChildrenHeight(cur)
@@ -836,16 +782,16 @@ func (avl *Tree) fixRemoveHeight(cur *Node) {
 		if diff < -1 {
 			r := cur.children[1] // 根据左旋转的右边节点的子节点 左右高度选择旋转的方式
 			if getHeight(r.children[0]) > getHeight(r.children[1]) {
-				avl.lrrotate(cur)
+				tree.lrrotate(cur)
 			} else {
-				avl.lrotate(cur)
+				tree.lrotate(cur)
 			}
 		} else if diff > 1 {
 			l := cur.children[0]
 			if getHeight(l.children[1]) > getHeight(l.children[0]) {
-				avl.rlrotate(cur)
+				tree.rlrotate(cur)
 			} else {
-				avl.rrotate(cur)
+				tree.rrotate(cur)
 			}
 		} else {
 			if cur.height == curheight {
@@ -862,7 +808,7 @@ func (avl *Tree) fixRemoveHeight(cur *Node) {
 
 }
 
-func (avl *Tree) fixPutHeight(cur *Node) {
+func (tree *Tree) fixPutHeight(cur *Node) {
 
 	for {
 
@@ -874,16 +820,16 @@ func (avl *Tree) fixPutHeight(cur *Node) {
 		if diff < -1 {
 			r := cur.children[1] // 根据左旋转的右边节点的子节点 左右高度选择旋转的方式
 			if getHeight(r.children[0]) > getHeight(r.children[1]) {
-				avl.lrrotate(cur)
+				tree.lrrotate(cur)
 			} else {
-				avl.lrotate(cur)
+				tree.lrotate(cur)
 			}
 		} else if diff > 1 {
 			l := cur.children[0]
 			if getHeight(l.children[1]) > getHeight(l.children[0]) {
-				avl.rlrotate(cur)
+				tree.rlrotate(cur)
 			} else {
-				avl.rrotate(cur)
+				tree.rrotate(cur)
 			}
 
 		} else {
@@ -973,11 +919,11 @@ func outputfordebug(node *Node, prefix string, isTail bool, str *string) {
 	}
 }
 
-func (avl *Tree) debugString() string {
+func (tree *Tree) debugString() string {
-	if avl.size == 0 {
+	if tree.size == 0 {
 		return ""
 	}
 	str := "AVLTree\n"
-	outputfordebug(avl.root, "", true, &str)
+	outputfordebug(tree.root, "", true, &str)
 	return str
 }

avl/avl_test.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"testing"
 
+	"474420502.top/eson/structure/compare"
 	"github.com/Pallinder/go-randomdata"
 	"github.com/davecgh/go-spew/spew"
 	"github.com/emirpasic/gods/trees/avltree"
@@ -80,57 +81,166 @@ func TestIterator(t *testing.T) {
 	// 			   └── 1`
 
 	iter := avl.Iterator() // root start point
-	t.Error(iter.cur, spew.Sdump(iter.tstack))
 	l := []int{14, 15, 20, 21, 30}
 
-	for i := 0; iter.Prev(); i++ {
+	for i := 0; iter.Next(); i++ {
 		if iter.Value().(int) != l[i] {
-			t.Error("iter prev error", iter.Value(), l[i])
+			t.Error("iter Next error", iter.Value(), l[i])
 		}
 	}
 
-	iter.Prev()
+	iter.Next()
 	if iter.Value().(int) != 30 {
-		t.Error("prev == false", iter.Value(), iter.Prev(), iter.Value())
+		t.Error("Next == false", iter.Value(), iter.Next(), iter.Value())
 	}
 
 	l = []int{21, 20, 15, 14, 7, 7, 6, 5, 4, 3, 2, 1}
-	t.Error(iter.cur, spew.Sdump(iter.tstack))
+	for i := 0; iter.Prev(); i++ { // cur is 30 next is 21
-	for i := 0; iter.Next(); i++ { // cur is 30 next is 21
 		if iter.Value().(int) != l[i] {
 			t.Error(iter.Value())
 		}
 	}
 
-	if iter.Next() != false {
+	if iter.Prev() != false {
-		t.Error("Next is error, cur is tail, val = 1 Next return false")
+		t.Error("Prev is error, cur is tail, val = 1 Prev return false")
 	}
 	if iter.Value().(int) != 1 { // cur is 1
-		t.Error("next == false", iter.Value(), iter.Next(), iter.Value())
+		t.Error("next == false", iter.Value(), iter.Prev(), iter.Value())
 	}
 
-	if iter.Prev() != true && iter.Value().(int) != 2 {
+	if iter.Next() != true && iter.Value().(int) != 2 {
 		t.Error("next to prev is error")
 	}
 }
 
+func TestGetRange(t *testing.T) {
+	tree := New(compare.Int)
+	for _, v := range []int{5, 6, 8, 10, 13, 17, 1, 2, 40, 30} {
+		tree.Put(v)
+	}
+
+	// t.Error(tree.debugString())
+	// t.Error(tree.getArountNode(20))
+	// t.Error(tree.Values())
+
+	result := tree.GetRange(0, 20)
+	if spew.Sprint(result) != "[1 2 5 6 8 10 13 17]" {
+		t.Error(result)
+	}
+
+	result = tree.GetRange(-5, -1)
+	if spew.Sprint(result) != "[]" {
+		t.Error(result)
+	}
+
+	result = tree.GetRange(7, 20)
+	if spew.Sprint(result) != "[8 10 13 17]" {
+		t.Error(result)
+	}
+
+	result = tree.GetRange(30, 40)
+	if spew.Sprint(result) != "[30 40]" {
+		t.Error(result)
+	}
+
+	result = tree.GetRange(30, 60)
+	if spew.Sprint(result) != "[30 40]" {
+		t.Error(result)
+	}
+
+	result = tree.GetRange(40, 40)
+	if spew.Sprint(result) != "[40]" {
+		t.Error(result)
+	}
+
+	result = tree.GetRange(50, 60)
+	if spew.Sprint(result) != "[]" {
+		t.Error(result)
+	}
+
+	result = tree.GetRange(50, 1)
+	if spew.Sprint(result) != "[40 30 17 13 10 8 6 5 2 1]" {
+		t.Error(result)
+	}
+
+	result = tree.GetRange(30, 20)
+	if spew.Sprint(result) != "[30]" {
+		t.Error(result)
+	}
+
+}
+
 func TestGetAround(t *testing.T) {
-	avl := New(utils.IntComparator)
+	tree := New(compare.Int)
-	for _, v := range []int{7, 14, 15, 20, 30, 21, 40, 40, 50, 3, 40, 40, 40} {
+	for _, v := range []int{7, 14, 14, 14, 16, 17, 20, 30, 21, 40, 50, 3, 40, 40, 40, 15} {
-		avl.Put(v)
+		tree.Put(v)
 	}
 
-	if spew.Sprint(avl.GetAround(30)) != "[40 30 21]" {
+	var Result string
-		t.Error("avl.GetAround(40)) is error", spew.Sprint(avl.GetAround(30)))
+
+	Result = spew.Sprint(tree.GetAround(14))
+	if Result != "[7 14 14]" {
+		t.Error(tree.Values())
+		t.Error("14 is root, tree.GetAround(14)) is error", Result)
+		t.Error(tree.debugString())
 	}
 
-	if spew.Sprint(avl.GetAround(40)) != "[40 40 30]" {
+	Result = spew.Sprint(tree.GetAround(17))
-		t.Error("avl.GetAround(40)) is error", spew.Sprint(avl.GetAround(40)))
+	if Result != "[16 17 20]" {
+		t.Error(tree.Values())
+		t.Error("tree.GetAround(17)) is error", Result)
+		t.Error(tree.debugString())
 	}
 
-	if spew.Sprint(avl.GetAround(50)) != "[<nil> 50 40]" {
+	Result = spew.Sprint(tree.GetAround(3))
-		t.Error("avl.GetAround(50)) is error", spew.Sprint(avl.GetAround(50)))
+	if Result != "[<nil> 3 7]" {
+		t.Error(tree.Values())
+		t.Error("tree.GetAround(3)) is error", Result)
+		t.Error(tree.debugString())
 	}
+
+	Result = spew.Sprint(tree.GetAround(40))
+	if Result != "[30 40 40]" {
+		t.Error(tree.Values())
+		t.Error("tree.GetAround(40)) is error", Result)
+		t.Error(tree.debugString())
+	}
+
+	Result = spew.Sprint(tree.GetAround(50))
+	if Result != "[40 50 <nil>]" {
+		t.Error(tree.Values())
+		t.Error("tree.GetAround(50)) is error", Result)
+		t.Error(tree.debugString())
+	}
+
+	Result = spew.Sprint(tree.GetAround(18))
+	if Result != "[17 <nil> 20]" {
+		t.Error(tree.Values())
+		t.Error("18 is not in list, tree.GetAround(18)) is error", Result)
+		t.Error(tree.debugString())
+	}
+
+	Result = spew.Sprint(tree.GetAround(5))
+	if Result != "[3 <nil> 7]" {
+		t.Error(tree.Values())
+		t.Error("5 is not in list, tree.GetAround(5)) is error", Result)
+		t.Error(tree.debugString())
+	}
+
+	Result = spew.Sprint(tree.GetAround(2))
+	if Result != "[<nil> <nil> 3]" {
+		t.Error(tree.Values())
+		t.Error("2 is not in list, tree.GetAround(2)) is error", Result)
+		t.Error(tree.debugString())
+	}
+
+	Result = spew.Sprint(tree.GetAround(100))
+	if Result != "[50 <nil> <nil>]" {
+		t.Error(tree.Values())
+		t.Error("50 is not in list, tree.GetAround(50)) is error", Result)
+		t.Error(tree.debugString())
+	}
+
 }
 
 // for test error case
@@ -300,7 +410,6 @@ func BenchmarkIterator(b *testing.B) {
 	tree := New(utils.IntComparator)
 
 	l := loadTestData()
-	b.N = len(l)
 
 	for _, v := range l {
 		tree.Put(v)
@@ -308,12 +417,19 @@ func BenchmarkIterator(b *testing.B) {
 
 	b.ResetTimer()
 	b.StartTimer()
+	b.N = 0
 	iter := tree.Iterator()
 	for iter.Next() {
+		b.N++
 	}
 	for iter.Prev() {
+		b.N++
 	}
 	for iter.Next() {
+		b.N++
+	}
+	for iter.Prev() {
+		b.N++
 	}
 
 }

avl/iterator.go

@@ -1,10 +1,6 @@
 package avl
 
 import (
-	"log"
-
-	"github.com/davecgh/go-spew/spew"
-
 	"474420502.top/eson/structure/lastack"
 )
 
@@ -50,63 +46,6 @@ func (iter *Iterator) Right() bool {
 	return false
 }
 
-func GetPrev(cur *Node, idx int) *Node {
-
-	iter := NewIterator(cur)
-	iter.curPushPrevStack(iter.up)
-	iter.up = iter.getPrevUp(iter.up)
-
-	for i := 0; i < idx; i++ {
-
-		if iter.tstack.Size() == 0 {
-			if iter.up == nil {
-				return nil
-			}
-			iter.tstack.Push(iter.up)
-			iter.up = iter.getPrevUp(iter.up)
-		}
-
-		if v, ok := iter.tstack.Pop(); ok {
-			iter.cur = v.(*Node)
-			if i == idx-1 {
-				return iter.cur
-			}
-			iter.curPushPrevStack(iter.cur)
-		} else {
-			return nil
-		}
-	}
-
-	return cur
-}
-
-func (iter *Iterator) Prev() (result bool) {
-
-	if iter.dir > -1 {
-		if iter.dir == 1 && iter.cur != nil {
-			iter.tstack.Clear()
-			iter.curPushPrevStack(iter.cur)
-			iter.up = iter.getPrevUp(iter.cur)
-		}
-		iter.dir = -1
-	}
-
-	if iter.tstack.Size() == 0 {
-		if iter.up == nil {
-			return false
-		}
-		iter.tstack.Push(iter.up)
-		iter.up = iter.getPrevUp(iter.up)
-	}
-
-	if v, ok := iter.tstack.Pop(); ok {
-		iter.cur = v.(*Node)
-		iter.curPushPrevStack(iter.cur)
-		return true
-	}
-
-	return false
-}
 func GetNext(cur *Node, idx int) *Node {
 
 	iter := NewIterator(cur)
@@ -139,16 +78,15 @@ func GetNext(cur *Node, idx int) *Node {
 
 func (iter *Iterator) Next() (result bool) {
 
-	if iter.dir < 1 { // 非 1(next 方向定义 -1 为 prev)
+	if iter.dir > -1 {
-		if iter.dir == -1 && iter.cur != nil { // 如果上次为prev方向, 则清空辅助计算的栈
+		if iter.dir == 1 && iter.cur != nil {
 			iter.tstack.Clear()
-			iter.curPushNextStack(iter.cur)    // 把当前cur计算的逆向回朔
+			iter.curPushNextStack(iter.cur)
-			iter.up = iter.getNextUp(iter.cur) // cur 寻找下个要计算up
+			iter.up = iter.getNextUp(iter.cur)
 		}
-		iter.dir = 1
+		iter.dir = -1
 	}
 
-	// 如果栈空了, 把up的递归计算入栈, 重新计算 下次的up值
 	if iter.tstack.Size() == 0 {
 		if iter.up == nil {
 			return false
@@ -163,6 +101,64 @@ func (iter *Iterator) Next() (result bool) {
 		return true
 	}
 
+	return false
+}
+func GetPrev(cur *Node, idx int) *Node {
+
+	iter := NewIterator(cur)
+	iter.curPushPrevStack(iter.up)
+	iter.up = iter.getPrevUp(iter.up)
+
+	for i := 0; i < idx; i++ {
+
+		if iter.tstack.Size() == 0 {
+			if iter.up == nil {
+				return nil
+			}
+			iter.tstack.Push(iter.up)
+			iter.up = iter.getPrevUp(iter.up)
+		}
+
+		if v, ok := iter.tstack.Pop(); ok {
+			iter.cur = v.(*Node)
+			if i == idx-1 {
+				return iter.cur
+			}
+			iter.curPushPrevStack(iter.cur)
+		} else {
+			return nil
+		}
+	}
+
+	return cur
+}
+
+func (iter *Iterator) Prev() (result bool) {
+
+	if iter.dir < 1 { // 非 1(next 方向定义 -1 为 prev)
+		if iter.dir == -1 && iter.cur != nil { // 如果上次为prev方向, 则清空辅助计算的栈
+			iter.tstack.Clear()
+			iter.curPushPrevStack(iter.cur)    // 把当前cur计算的逆向回朔
+			iter.up = iter.getPrevUp(iter.cur) // cur 寻找下个要计算up
+		}
+		iter.dir = 1
+	}
+
+	// 如果栈空了, 把up的递归计算入栈, 重新计算 下次的up值
+	if iter.tstack.Size() == 0 {
+		if iter.up == nil {
+			return false
+		}
+		iter.tstack.Push(iter.up)
+		iter.up = iter.getPrevUp(iter.up)
+	}
+
+	if v, ok := iter.tstack.Pop(); ok {
+		iter.cur = v.(*Node)
+		iter.curPushPrevStack(iter.cur)
+		return true
+	}
+
 	// 如果再次计算的栈为空, 则只能返回false
 	return false
 }
@@ -174,7 +170,7 @@ func getRelationship(cur *Node) int {
 	return 0
 }
 
-func (iter *Iterator) getNextUp(cur *Node) *Node {
+func (iter *Iterator) getPrevUp(cur *Node) *Node {
 	for cur.parent != nil {
 		if getRelationship(cur) == 1 { // next 在 降序 小值. 如果child在右边, parent 比 child 小, parent才有效, 符合降序
 			return cur.parent
@@ -184,20 +180,19 @@ func (iter *Iterator) getNextUp(cur *Node) *Node {
 	return nil
 }
 
-func (iter *Iterator) curPushNextStack(cur *Node) {
+func (iter *Iterator) curPushPrevStack(cur *Node) {
-	next := cur.children[0] // 当前的左然后向右找, 找到最大, 就是最接近cur 并且小于cur的值
+	Prev := cur.children[0] // 当前的左然后向右找, 找到最大, 就是最接近cur 并且小于cur的值
 
-	if next != nil {
+	if Prev != nil {
-		log.Println(spew.Sdump(iter.tstack))
+		iter.tstack.Push(Prev)
-		iter.tstack.Push(next)
+		for Prev.children[1] != nil {
-		for next.children[1] != nil {
+			Prev = Prev.children[1]
-			next = next.children[1]
+			iter.tstack.Push(Prev) // 入栈 用于回溯
-			iter.tstack.Push(next) // 入栈 用于回溯
 		}
 	}
 }
 
-func (iter *Iterator) getPrevUp(cur *Node) *Node {
+func (iter *Iterator) getNextUp(cur *Node) *Node {
 	for cur.parent != nil {
 		if getRelationship(cur) == 0 { // Prev 在 降序 大值. 如果child在左边, parent 比 child 大, parent才有效 , 符合降序
 			return cur.parent
@@ -207,14 +202,14 @@ func (iter *Iterator) getPrevUp(cur *Node) *Node {
 	return nil
 }
 
-func (iter *Iterator) curPushPrevStack(cur *Node) {
+func (iter *Iterator) curPushNextStack(cur *Node) {
-	prev := cur.children[1]
+	next := cur.children[1]
 
-	if prev != nil {
+	if next != nil {
-		iter.tstack.Push(prev)
+		iter.tstack.Push(next)
-		for prev.children[0] != nil {
+		for next.children[0] != nil {
-			prev = prev.children[0]
+			next = next.children[0]
-			iter.tstack.Push(prev)
+			iter.tstack.Push(next)
 		}
 	}
 }

lastack/lastack_test.go

@@ -56,7 +56,7 @@ func BenchmarkGet(b *testing.B) {
 
 func BenchmarkPush(b *testing.B) {
 	s := New()
-	b.N = 200000
+	b.N = 20000000
 	for i := 0; i < b.N; i++ {
 		v := randomdata.Number(0, 65535)
 		s.Push(v)
@@ -65,7 +65,7 @@ func BenchmarkPush(b *testing.B) {
 
 func BenchmarkGodsPush(b *testing.B) {
 	s := arraystack.New()
-	b.N = 200000
+	b.N = 2000000
 	for i := 0; i < b.N; i++ {
 		v := randomdata.Number(0, 65535)
 		s.Push(v)
@@ -74,7 +74,7 @@ func BenchmarkGodsPush(b *testing.B) {
 
 func BenchmarkPop(b *testing.B) {
 	s := New()
-	b.N = 200000
+	b.N = 2000000
 
 	for i := 0; i < b.N; i++ {
 		v := randomdata.Number(0, 65535)
@@ -91,7 +91,7 @@ func BenchmarkPop(b *testing.B) {
 
 func BenchmarkGodsPop(b *testing.B) {
 	s := arraystack.New()
-	b.N = 200
+	b.N = 2000000
 
 	for i := 0; i < b.N; i++ {
 		v := randomdata.Number(0, 65535)

stack/stack_test.go

@@ -28,7 +28,7 @@ func BenchmarkGodsPush(b *testing.B) {
 
 func BenchmarkPop(b *testing.B) {
 	s := New()
-	b.N = 200
+	b.N = 200000
 
 	for i := 0; i < b.N; i++ {
 		v := randomdata.Number(0, 65535)
@@ -45,7 +45,7 @@ func BenchmarkPop(b *testing.B) {
 
 func BenchmarkGodsPop(b *testing.B) {
 	s := arraystack.New()
-	b.N = 200
+	b.N = 200000
 
 	for i := 0; i < b.N; i++ {
 		v := randomdata.Number(0, 65535)