This commit is contained in:
huangsimin 2019-03-15 19:58:05 +08:00
parent 3e16572b12
commit d708418f75
3 changed files with 1150 additions and 0 deletions

541
avlindex/avlindex.go Normal file
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package avlindex
import (
"github.com/davecgh/go-spew/spew"
"github.com/emirpasic/gods/utils"
)
type Node struct {
children [2]*Node
parent *Node
size int
value interface{}
}
func (n *Node) String() string {
if n == nil {
return "nil"
}
p := "nil"
if n.parent != nil {
p = spew.Sprint(n.parent.value)
}
return spew.Sprint(n.value) + "(" + p + "|" + spew.Sprint(n.size) + ")"
}
type Tree struct {
root *Node
comparator utils.Comparator
}
func New(comparator utils.Comparator) *Tree {
return &Tree{comparator: comparator}
}
func (avl *Tree) String() string {
str := "AVLTree\n"
output(avl.root, "", true, &str)
return str
}
func (avl *Tree) Iterator() *Iterator {
return initIterator(avl)
}
func (avl *Tree) Size() int {
return avl.root.size
}
func (avl *Tree) Remove(key interface{}) *Node {
return nil
}
func (avl *Tree) Get(key interface{}) (interface{}, bool) {
n, ok := avl.GetNode(key)
if ok {
return n.value, true
}
return n, false
}
func (avl *Tree) GetRange(min, max interface{}) []interface{} {
return nil
}
func (avl *Tree) GetAround(key interface{}) (result [3]interface{}) {
an := avl.GetAroundNode(key)
for i, n := range an {
if n != nil {
result[i] = n.value
}
}
return
}
func (avl *Tree) GetAroundNode(value interface{}) (result [3]*Node) {
n := avl.root
for {
if n == nil {
return
}
lastc := 0
switch c := avl.comparator(value, n.value); c {
case -1:
if c != -lastc {
result[0] = n
}
lastc = c
n = n.children[0]
case 1:
if c != -lastc {
result[2] = n
}
lastc = c
n = n.children[1]
case 0:
switch lastc {
case -1:
if n.children[1] != nil {
result[0] = n.children[1]
}
case 1:
if n.children[0] != nil {
result[2] = n.children[0]
}
case 0:
if n.children[1] != nil {
result[0] = n.children[1]
}
if n.children[0] != nil {
result[2] = n.children[0]
}
result[1] = n
return
}
default:
panic("Get comparator only is allowed in -1, 0, 1")
}
}
}
func (avl *Tree) GetNode(value interface{}) (*Node, bool) {
for n := avl.root; n != nil; {
switch c := avl.comparator(value, n.value); c {
case -1:
n = n.children[0]
case 1:
n = n.children[1]
case 0:
return n, true
default:
panic("Get comparator only is allowed in -1, 0, 1")
}
}
return nil, false
}
func (avl *Tree) Put(value interface{}) {
node := &Node{value: value, size: 1}
if avl.root == nil {
avl.root = node
return
}
cur := avl.root
parent := cur.parent
child := -1
for {
if cur == nil {
parent.children[child] = node
node.parent = parent
if getSize(node.parent.parent) == 3 {
lefts, rigths := getChildrenSize(node.parent.parent)
avl.fixPutHeight(node.parent.parent, lefts, rigths)
}
return
}
if cur.size > 4 {
ls, rs := getChildrenSize(cur)
if rs > ls {
if rs >= ls*2 {
avl.fixPutHeight(cur, ls, rs)
}
} else {
if ls >= rs*2 {
avl.fixPutHeight(cur, ls, rs)
}
}
}
cur.size++
parent = cur
c := avl.comparator(value, cur.value)
child = (c + 2) / 2
cur = cur.children[child]
}
}
func (avl *Tree) debugString() string {
str := "AVLTree\n"
outputfordebug(avl.root, "", true, &str)
return str
}
func (avl *Tree) TraversalBreadth() (result []interface{}) {
result = make([]interface{}, 0, avl.root.size)
var traverasl func(cur *Node)
traverasl = func(cur *Node) {
if cur == nil {
return
}
result = append(result, cur.value)
traverasl(cur.children[0])
traverasl(cur.children[1])
}
traverasl(avl.root)
return
}
func (avl *Tree) TraversalDepth(leftright int) (result []interface{}) {
result = make([]interface{}, 0, avl.root.size)
if leftright < 0 {
var traverasl func(cur *Node)
traverasl = func(cur *Node) {
if cur == nil {
return
}
traverasl(cur.children[0])
result = append(result, cur.value)
traverasl(cur.children[1])
}
traverasl(avl.root)
} else {
var traverasl func(cur *Node)
traverasl = func(cur *Node) {
if cur == nil {
return
}
traverasl(cur.children[1])
result = append(result, cur.value)
traverasl(cur.children[0])
}
traverasl(avl.root)
}
return
}
func (avl *Tree) lrrotate(cur *Node) {
const l = 1
const r = 0
movparent := cur.children[l]
mov := movparent.children[r]
mov.value, cur.value = cur.value, mov.value //交换值达到, 相对位移
if mov.children[l] != nil {
movparent.children[r] = mov.children[l]
movparent.children[r].parent = movparent
//movparent.children[r].child = l
} else {
movparent.children[r] = nil
}
if mov.children[r] != nil {
mov.children[l] = mov.children[r]
//mov.children[l].child = l
} else {
mov.children[l] = nil
}
if cur.children[r] != nil {
mov.children[r] = cur.children[r]
mov.children[r].parent = mov
} else {
mov.children[r] = nil
}
cur.children[r] = mov
mov.parent = cur
// cur.size = 3
// cur.children[0].size = 1
// cur.children[1].size = 1
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
}
func (avl *Tree) rlrotate(cur *Node) {
const l = 0
const r = 1
movparent := cur.children[l]
mov := movparent.children[r]
mov.value, cur.value = cur.value, mov.value //交换值达到, 相对位移
if mov.children[l] != nil {
movparent.children[r] = mov.children[l]
movparent.children[r].parent = movparent
} else {
movparent.children[r] = nil
}
if mov.children[r] != nil {
mov.children[l] = mov.children[r]
} else {
mov.children[l] = nil
}
if cur.children[r] != nil {
mov.children[r] = cur.children[r]
mov.children[r].parent = mov
} else {
mov.children[r] = nil
}
cur.children[r] = mov
mov.parent = cur
movparent.size = getChildrenSumSize(movparent) + 1
mov.size = getChildrenSumSize(mov) + 1
cur.size = getChildrenSumSize(cur) + 1
// cur.size = 3
// cur.children[0].size = 1
// cur.children[1].size = 1
// mov.height = getMaxChildrenHeight(mov) + 1
// movparent.height = getMaxChildrenHeight(movparent) + 1
// cur.height = getMaxChildrenHeight(cur) + 1
}
func (avl *Tree) rrotate(cur *Node) {
const l = 0
const r = 1
// 1 right 0 left
mov := cur.children[l]
// lsize, rsize := getChildrenHeight(cur)
// movrsize := getSize(mov.children[r])
mov.value, cur.value = cur.value, mov.value //交换值达到, 相对位移
// mov.children[l]不可能为nil
mov.children[l].parent = cur
cur.children[l] = mov.children[l]
// 解决mov节点孩子转移的问题
if mov.children[r] != nil {
mov.children[l] = mov.children[r]
} else {
mov.children[l] = nil
}
if cur.children[r] != nil {
mov.children[r] = cur.children[r]
mov.children[r].parent = mov
} else {
mov.children[r] = nil
}
// 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
// cur.size = 3
// cur.children[0].size = 1
// cur.children[1].size = 1
mov.size = getChildrenSumSize(mov) + 1
cur.size = getChildrenSumSize(cur) + 1
// cur.height = getMaxChildrenHeight(cur) + 1
}
func (avl *Tree) lrotate(cur *Node) {
const l = 1
const r = 0
// 1 right 0 left
mov := cur.children[l]
// lsize, rsize := getChildrenHeight(cur)
// movrsize := getSize(mov.children[r])
mov.value, cur.value = cur.value, mov.value //交换值达到, 相对位移
// mov.children[l]不可能为nil
mov.children[l].parent = cur
cur.children[l] = mov.children[l]
// 解决mov节点孩子转移的问题
if mov.children[r] != nil {
mov.children[l] = mov.children[r]
} else {
mov.children[l] = nil
}
if cur.children[r] != nil {
mov.children[r] = cur.children[r]
mov.children[r].parent = mov
} else {
mov.children[r] = nil
}
// 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
// cur.size = 3
// cur.children[0].size = 1
// cur.children[1].size = 1
mov.size = getChildrenSumSize(mov) + 1
cur.size = getChildrenSumSize(cur) + 1
}
func getChildrenSumSize(cur *Node) int {
return getSize(cur.children[0]) + getSize(cur.children[1])
}
func getChildrenSize(cur *Node) (int, int) {
return getSize(cur.children[0]), getSize(cur.children[1])
}
func getSize(cur *Node) int {
if cur == nil {
return 0
}
return cur.size
}
func (avl *Tree) fixRemoveHeight(cur *Node) {
}
func abs(n int) int {
y := n >> 31
return (n ^ y) - y
}
func (avl *Tree) fixPutHeight(cur *Node, lefts, rigths int) {
// lefts, rigths := getChildrenSize(cur)
if lefts < rigths {
r := cur.children[1]
rlsize, rrsize := getChildrenSize(r)
if rlsize > rrsize {
avl.lrrotate(cur)
} else {
avl.lrotate(cur)
}
} else {
l := cur.children[0]
llsize, lrsize := getChildrenSize(l)
if lrsize > llsize {
avl.rlrotate(cur)
} else {
avl.rrotate(cur)
}
}
}
func output(node *Node, prefix string, isTail bool, str *string) {
if node.children[1] != nil {
newPrefix := prefix
if isTail {
newPrefix += "│ "
} else {
newPrefix += " "
}
output(node.children[1], newPrefix, false, str)
}
*str += prefix
if isTail {
*str += "└── "
} else {
*str += "┌── "
}
*str += spew.Sprint(node.value) + "\n"
if node.children[0] != nil {
newPrefix := prefix
if isTail {
newPrefix += " "
} else {
newPrefix += "│ "
}
output(node.children[0], newPrefix, true, str)
}
}
func outputfordebug(node *Node, prefix string, isTail bool, str *string) {
if node.children[1] != nil {
newPrefix := prefix
if isTail {
newPrefix += "│ "
} else {
newPrefix += " "
}
outputfordebug(node.children[1], newPrefix, false, str)
}
*str += prefix
if isTail {
*str += "└── "
} else {
*str += "┌── "
}
suffix := "("
parentv := ""
if node.parent == nil {
parentv = "nil"
} else {
parentv = spew.Sprint(node.parent.value)
}
suffix += parentv + "|" + spew.Sprint(node.size) + ")"
*str += spew.Sprint(node.value) + suffix + "\n"
if node.children[0] != nil {
newPrefix := prefix
if isTail {
newPrefix += " "
} else {
newPrefix += "│ "
}
outputfordebug(node.children[0], newPrefix, true, str)
}
}

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avlindex/avlindex_test.go Normal file
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package avlindex
import (
"bytes"
"encoding/gob"
"io/ioutil"
"log"
"os"
"testing"
"github.com/Pallinder/go-randomdata"
"github.com/emirpasic/gods/trees/avltree"
"github.com/emirpasic/gods/trees/redblacktree"
"github.com/emirpasic/gods/utils"
)
const CompartorSize = 10000000
const NumberMax = 60000000
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)
}
//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 {
log.Println(err)
}
var l []int
decoder := gob.NewDecoder(bytes.NewReader(data))
decoder.Decode(&l)
return l
}
// func TestIterator(t *testing.T) {
// avl := New(utils.IntComparator)
// for _, v := range []int{1, 2, 7, 4, 5, 6, 7, 14, 15, 20, 30, 21, 3} {
// // t.Error(v)
// avl.Put(v)
// }
// // ` AVLTree
// // │ ┌── 30
// // │ │ └── 21
// // │ ┌── 20
// // │ │ └── 15
// // └── 14
// // │ ┌── 7
// // │ ┌── 7
// // │ │ └── 6
// // └── 5
// // │ ┌── 4
// // │ │ └── 3
// // └── 2
// // └── 1`
// iter := avl.Iterator() // root start point
// l := []int{14, 15, 20, 21, 30}
// for i := 0; iter.Prev(); i++ {
// if iter.Value().(int) != l[i] {
// t.Error("iter prev error", iter.Value(), l[i])
// }
// }
// iter.Prev()
// if iter.Value().(int) != 30 {
// t.Error("prev == false", iter.Value(), iter.Prev(), iter.Value())
// }
// l = []int{21, 20, 15, 14, 7, 7, 6, 5, 4, 3, 2, 1}
// 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 {
// t.Error("Next is error, cur is tail, val = 1 Next return false")
// }
// if iter.Value().(int) != 1 { // cur is 1
// t.Error("next == false", iter.Value(), iter.Next(), iter.Value())
// }
// if iter.Prev() != true && iter.Value().(int) != 2 {
// t.Error("next to prev is error")
// }
// }
// func TestGetAround(t *testing.T) {
// avl := New(utils.IntComparator)
// for _, v := range []int{7, 14, 15, 20, 30, 21, 40, 40, 50, 3, 40, 40, 40} {
// avl.Put(v)
// }
// if spew.Sprint(avl.GetAround(30)) != "[40 30 21]" {
// t.Error("avl.GetAround(40)) is error", spew.Sprint(avl.GetAround(30)))
// }
// if spew.Sprint(avl.GetAround(40)) != "[40 40 30]" {
// t.Error("avl.GetAround(40)) is error", spew.Sprint(avl.GetAround(50)))
// }
// if spew.Sprint(avl.GetAround(50)) != "[<nil> 50 40]" {
// t.Error("avl.GetAround(40)) is error", spew.Sprint(avl.GetAround(50)))
// }
// }
// // for test error case
// func TestPutComparatorRandom(t *testing.T) {
// for n := 0; n < 300000; n++ {
// avl := New(utils.IntComparator)
// godsavl := avltree.NewWithIntComparator()
// content := ""
// m := make(map[int]int)
// for i := 0; len(m) < 10; i++ {
// v := randomdata.Number(0, 65535)
// if _, ok := m[v]; !ok {
// m[v] = v
// content += spew.Sprint(v) + ","
// avl.Put(v)
// godsavl.Put(v, v)
// }
// }
// if avl.String() != godsavl.String() {
// t.Error(godsavl.String())
// t.Error(avl.debugString())
// t.Error(content, n)
// break
// }
// }
// }
func TestGet(t *testing.T) {
avl := New(utils.IntComparator)
for _, v := range []int{2383, 7666, 3055, 39016, 57092, 27897, 36513, 1562, 22574, 23202} {
avl.Put(v)
}
for _, v := range []int{2383, 7666, 3055, 39016, 57092, 27897, 36513, 1562, 22574, 23202} {
v, ok := avl.Get(v)
if !ok {
t.Error("the val not found ", v)
}
}
if v, ok := avl.Get(10000); ok {
t.Error("the val(1000) is not in tree, but is found", v)
}
}
// func TestRemoveAll(t *testing.T) {
// ALL:
// for c := 0; c < 5000; c++ {
// avl := New(utils.IntComparator)
// gods := avltree.NewWithIntComparator()
// var l []int
// m := make(map[int]int)
// for i := 0; len(l) < 100; i++ {
// v := randomdata.Number(0, 100000)
// if _, ok := m[v]; !ok {
// m[v] = v
// l = append(l, v)
// avl.Put(v)
// gods.Put(v, v)
// }
// }
// for i := 0; i < 100; i++ {
// avl.Remove(l[i])
// gods.Remove(l[i])
// s1 := spew.Sprint(avl.TraversalDepth(-1))
// s2 := spew.Sprint(gods.Values())
// if s1 != s2 {
// t.Error("avl remove error", "avlsize = ", avl.Size())
// t.Error(s1)
// t.Error(s2)
// break ALL
// }
// }
// }
// }
// func TestRemove(t *testing.T) {
// ALL:
// for N := 0; N < 500000; N++ {
// avl := New(utils.IntComparator)
// gods := avltree.NewWithIntComparator()
// var l []int
// m := make(map[int]int)
// for i := 0; len(l) < 10; i++ {
// v := randomdata.Number(0, 100)
// if _, ok := m[v]; !ok {
// l = append(l, v)
// m[v] = v
// avl.Put(v)
// gods.Put(v, v)
// }
// }
// src1 := avl.String()
// src2 := gods.String()
// for i := 0; i < 10; i++ {
// avl.Remove(l[i])
// gods.Remove(l[i])
// if spew.Sprint(gods.Values()) != spew.Sprint(avl.TraversalDepth(-1)) && avl.size != 0 {
// // if gods.String() != avl.String() && gods.Size() != 0 && avl.size != 0 {
// t.Error(src1)
// t.Error(src2)
// t.Error(avl.debugString())
// t.Error(gods.String())
// t.Error(l[i])
// // t.Error(avl.TraversalDepth(-1))
// // t.Error(gods.Values())
// break ALL
// }
// }
// }
// }
// func BenchmarkIterator(b *testing.B) {
// tree := New(utils.IntComparator)
// l := loadTestData()
// b.N = len(l)
// for _, v := range l {
// tree.Put(v)
// }
// b.ResetTimer()
// b.StartTimer()
// iter := tree.Iterator()
// for iter.Next() {
// }
// for iter.Prev() {
// }
// for iter.Next() {
// }
// }
// func BenchmarkGodsIterator(b *testing.B) {
// tree := avltree.NewWithIntComparator()
// l := loadTestData()
// b.N = len(l)
// for _, v := range l {
// tree.Put(v, v)
// }
// b.ResetTimer()
// b.StartTimer()
// iter := tree.Iterator()
// for iter.Next() {
// }
// for iter.Prev() {
// }
// for iter.Next() {
// }
// }
// func BenchmarkRemove(b *testing.B) {
// tree := New(utils.IntComparator)
// l := loadTestData()
// b.N = len(l)
// for _, v := range l {
// tree.Put(v)
// }
// b.ResetTimer()
// b.StartTimer()
// for i := 0; i < len(l); i++ {
// tree.Remove(l[i])
// }
// }
// func BenchmarkGodsRemove(b *testing.B) {
// tree := avltree.NewWithIntComparator()
// l := loadTestData()
// b.N = len(l)
// for _, v := range l {
// tree.Put(v, v)
// }
// b.ResetTimer()
// b.StartTimer()
// for i := 0; i < len(l); i++ {
// tree.Remove(l[i])
// }
// }
// func BenchmarkGodsRBRemove(b *testing.B) {
// tree := redblacktree.NewWithIntComparator()
// l := loadTestData()
// b.N = len(l)
// for _, v := range l {
// tree.Put(v, v)
// }
// b.ResetTimer()
// b.StartTimer()
// for i := 0; i < len(l); i++ {
// tree.Remove(l[i])
// }
// }
func BenchmarkGet(b *testing.B) {
avl := New(utils.IntComparator)
l := loadTestData()
b.N = len(l)
b.ResetTimer()
b.StartTimer()
for i := 0; i < b.N; i++ {
avl.Get(l[i])
}
}
// func BenchmarkGodsRBGet(b *testing.B) {
// tree := redblacktree.NewWithIntComparator()
// l := loadTestData()
// b.N = len(l)
// b.ResetTimer()
// b.StartTimer()
// for i := 0; i < b.N; i++ {
// tree.Get(l[i])
// }
// }
// func BenchmarkGodsAvlGet(b *testing.B) {
// tree := avltree.NewWithIntComparator()
// l := loadTestData()
// b.N = len(l)
// b.ResetTimer()
// b.StartTimer()
// for i := 0; i < b.N; i++ {
// tree.Get(l[i])
// }
// }
func BenchmarkPut(b *testing.B) {
avl := New(utils.IntComparator)
l := loadTestData()
b.ResetTimer()
b.StartTimer()
b.N = len(l)
for _, v := range l {
avl.Put(v)
}
}
func TestPutStable(t *testing.T) {
// l := []int{14, 18, 19, 20, 5, 6, 7, 8, 9, 21, 22, 30, 41, 41, 41, 0, 1, 2, 3, 4, 10, 11, 12, 13}
var l []int
for i := 0; len(l) < 100; i++ {
l = append(l, randomdata.Number(0, 65535))
}
for i := 0; len(l) < 1000; i++ {
l = append(l, randomdata.Number(70, 100))
}
avl := New(utils.IntComparator)
for _, v := range l {
avl.Put(v)
}
t.Error(len(l), avl.debugString(), avl.TraversalBreadth(), "\n", "-----------")
}
func BenchmarkGodsRBPut(b *testing.B) {
tree := redblacktree.NewWithIntComparator()
l := loadTestData()
b.ResetTimer()
b.StartTimer()
b.N = len(l)
for _, v := range l {
tree.Put(v, v)
}
}
func BenchmarkGodsPut(b *testing.B) {
tree := avltree.NewWithIntComparator()
l := loadTestData()
b.ResetTimer()
b.StartTimer()
b.N = len(l)
for _, v := range l {
tree.Put(v, v)
}
}

156
avlindex/iterator.go Normal file
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@ -0,0 +1,156 @@
package avlindex
import (
"474420502.top/eson/structure/lastack"
)
type Iterator struct {
op *Tree
dir int
up *Node
cur *Node
tstack *lastack.Stack
// curnext *Node
}
func initIterator(avltree *Tree) *Iterator {
iter := &Iterator{op: avltree, tstack: lastack.New()}
iter.up = avltree.root
return iter
}
func NewIterator(tree *Tree) *Iterator {
return initIterator(tree)
}
func (iter *Iterator) Value() interface{} {
return iter.cur.value
}
func (iter *Iterator) Left() bool {
if iter.cur.children[0] != nil {
iter.dir = 0
iter.cur = iter.cur.children[0]
return true
}
return false
}
func (iter *Iterator) Right() bool {
if iter.cur.children[1] != nil {
iter.dir = 0
iter.cur = iter.cur.children[1]
return true
}
return false
}
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 (iter *Iterator) Next() (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.curPushNextStack(iter.cur) // 把当前cur计算的逆向回朔
iter.up = iter.getNextUp(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.getNextUp(iter.up)
}
if v, ok := iter.tstack.Pop(); ok {
iter.cur = v.(*Node)
iter.curPushNextStack(iter.cur)
return true
}
// 如果再次计算的栈为空, 则只能返回false
return false
}
func getRelationship(cur *Node) int {
if cur.parent.children[1] == cur {
return 1
}
return 0
}
func (iter *Iterator) getNextUp(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
}
cur = cur.parent
}
return nil
}
func (iter *Iterator) curPushNextStack(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
if next != nil {
iter.tstack.Push(next)
for next.children[1] != nil {
next = next.children[1]
iter.tstack.Push(next) // 入栈 用于回溯
}
}
}
func (iter *Iterator) getPrevUp(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
}
cur = cur.parent
}
return nil
}
func (iter *Iterator) curPushPrevStack(cur *Node) {
prev := cur.children[1]
if prev != nil {
iter.tstack.Push(prev)
for prev.children[0] != nil {
prev = prev.children[0]
iter.tstack.Push(prev)
}
}
}