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https://github.com/duke-git/lancet.git
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feat: add DoublyLink data structure
This commit is contained in:
dudaodong
228
datastructure/doublylink.go
Normal file
228
datastructure/doublylink.go
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@@ -0,0 +1,228 @@
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package datastructure
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import (
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"errors"
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"fmt"
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)
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// DoublyLink is a linked list. Whose node has a generic Value, Pre pointer points to a previous node of the link, Next pointer points to a next node of the link.
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type DoublyLink[T any] struct {
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Head *LinkNode[T]
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length int
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}
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// NewDoublyLink return *DoublyLink instance
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func NewDoublyLink[T any]() *DoublyLink[T] {
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return &DoublyLink[T]{Head: nil}
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}
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// InsertAtHead insert value into doubly linklist at head index
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func (link *DoublyLink[T]) InsertAtHead(value T) {
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newNode := NewLinkNode(value)
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size := link.Size()
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if size == 0 {
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link.Head = newNode
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link.length++
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return
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}
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newNode.Next = link.Head
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newNode.Pre = nil
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link.Head.Pre = newNode
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link.Head = newNode
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link.length++
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}
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// InsertAtTail insert value into doubly linklist at tail index
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func (link *DoublyLink[T]) InsertAtTail(value T) {
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current := link.Head
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if current == nil {
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link.InsertAtHead(value)
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return
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}
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for current.Next != nil {
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current = current.Next
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}
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newNode := NewLinkNode(value)
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newNode.Next = nil
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newNode.Pre = current
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current.Next = newNode
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link.length++
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}
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// InsertAt insert value into doubly linklist at index
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func (link *DoublyLink[T]) InsertAt(index int, value T) error {
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size := link.length
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if index < 0 || index > size {
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return errors.New("param index should between 0 and the length of doubly link.")
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}
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if index == 0 {
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link.InsertAtHead(value)
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return nil
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}
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if index == size {
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link.InsertAtTail(value)
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return nil
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}
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i := 0
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current := link.Head
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for current != nil {
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if i == index-1 {
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newNode := NewLinkNode(value)
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newNode.Next = current.Next
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newNode.Pre = current
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current.Next = newNode
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link.length++
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return nil
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}
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i++
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current = current.Next
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}
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return errors.New("doubly link list no exist")
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}
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// DeleteAtHead delete value in doubly linklist at head index
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func (link *DoublyLink[T]) DeleteAtHead() error {
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if link.Head == nil {
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return errors.New("doubly link list no exist")
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}
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current := link.Head
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link.Head = current.Next
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link.Head.Pre = nil
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link.length--
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return nil
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}
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// DeleteAtTail delete value in doubly linklist at tail index
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func (link *DoublyLink[T]) DeleteAtTail() error {
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if link.Head == nil {
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return errors.New("doubly link list no exist")
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}
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current := link.Head
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if current.Next == nil {
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return link.DeleteAtHead()
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}
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for current.Next.Next != nil {
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current = current.Next
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}
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current.Next = nil
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link.length--
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return nil
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}
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// DeleteAt delete value in doubly linklist at index
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func (link *DoublyLink[T]) DeleteAt(index int) error {
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if link.Head == nil {
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return errors.New("doubly link list no exist")
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}
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current := link.Head
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if current.Next == nil || index == 0 {
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return link.DeleteAtHead()
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}
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if index == link.length-1 {
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return link.DeleteAtTail()
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}
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if index < 0 || index > link.length-1 {
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return errors.New("param index should between 0 and link size -1.")
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}
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i := 0
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for current != nil {
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if i == index-1 {
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current.Next = current.Next.Next
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link.length--
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return nil
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}
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i++
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current = current.Next
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}
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return errors.New("delete error")
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}
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// Reverse the linked list
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func (link *DoublyLink[T]) Reverse() {
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current := link.Head
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var temp *LinkNode[T]
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for current != nil {
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temp = current.Pre
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current.Pre = current.Next
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current.Next = temp
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current = current.Pre
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}
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if temp != nil {
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link.Head = temp.Pre
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}
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}
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// GetMiddleNode return node at middle index of linked list
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func (link *DoublyLink[T]) GetMiddleNode() *LinkNode[T] {
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if link.Head == nil {
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return nil
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}
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if link.Head.Next == nil {
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return link.Head
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}
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fast := link.Head
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slow := link.Head
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for fast != nil {
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fast = fast.Next
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if fast != nil {
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fast = fast.Next
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slow = slow.Next
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} else {
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return slow
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}
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}
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return slow
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}
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// Size return the count of doubly linked list
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func (link *DoublyLink[T]) Size() int {
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return link.length
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}
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// Values return slice of all doubly linklist node value
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func (link *DoublyLink[T]) Values() []T {
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res := []T{}
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current := link.Head
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for current != nil {
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res = append(res, current.Value)
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current = current.Next
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}
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return res
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}
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// Print all nodes info of a linked list
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func (link *DoublyLink[T]) Print() {
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current := link.Head
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info := "[ "
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for current != nil {
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info += fmt.Sprintf("%+v, ", current)
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current = current.Next
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}
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info += " ]"
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fmt.Println(info)
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}
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165
datastructure/doublylink_test.go
Normal file
165
datastructure/doublylink_test.go
Normal file
@@ -0,0 +1,165 @@
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package datastructure
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import (
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"testing"
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"github.com/duke-git/lancet/internal"
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)
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func TestDoublyLink_InsertAtFirst(t *testing.T) {
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assert := internal.NewAssert(t, "TestDoublyLink_InsertAtFirst")
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link := NewDoublyLink[int]()
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link.InsertAtHead(1)
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link.InsertAtHead(2)
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link.InsertAtHead(3)
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link.Print()
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expected := []int{3, 2, 1}
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values := link.Values()
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assert.Equal(expected, values)
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}
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func TestDoublyLink_InsertAtTail(t *testing.T) {
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assert := internal.NewAssert(t, "TestDoublyLink_InsertAtTail")
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link := NewDoublyLink[int]()
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link.InsertAtTail(1)
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link.InsertAtTail(2)
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link.InsertAtTail(3)
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link.Print()
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expected := []int{1, 2, 3}
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values := link.Values()
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assert.Equal(expected, values)
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}
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func TestDoublyLink_InsertAt(t *testing.T) {
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assert := internal.NewAssert(t, "TestDoublyLink_InsertAt")
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link := NewDoublyLink[int]()
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err := link.InsertAt(1, 1)
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assert.IsNotNil(err)
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err = link.InsertAt(0, 1)
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err = link.InsertAt(1, 2)
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err = link.InsertAt(2, 4)
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err = link.InsertAt(2, 3)
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if err != nil {
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t.FailNow()
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}
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link.Print()
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expected := []int{1, 2, 3, 4}
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values := link.Values()
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assert.Equal(expected, values)
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}
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func TestDoublyLink_DeleteAtHead(t *testing.T) {
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assert := internal.NewAssert(t, "TestDoublyLink_DeleteAtHead")
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link := NewDoublyLink[int]()
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err := link.DeleteAtHead()
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assert.IsNotNil(err)
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link.InsertAtTail(1)
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link.InsertAtTail(2)
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link.InsertAtTail(3)
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link.InsertAtTail(4)
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link.DeleteAtHead()
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link.Print()
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expected := []int{2, 3, 4}
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values := link.Values()
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assert.Equal(expected, values)
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}
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func TestDoublyLink_DeleteAtTail(t *testing.T) {
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assert := internal.NewAssert(t, "TestDoublyLink_DeleteAtTail")
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link := NewDoublyLink[int]()
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err := link.DeleteAtTail()
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assert.IsNotNil(err)
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link.InsertAtTail(1)
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link.InsertAtTail(2)
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link.InsertAtTail(3)
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link.InsertAtTail(4)
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link.DeleteAtTail()
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link.Print()
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expected := []int{1, 2, 3}
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values := link.Values()
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assert.Equal(expected, values)
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}
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func TestDoublyLink_DeleteAt(t *testing.T) {
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assert := internal.NewAssert(t, "TestDoublyLink_DeleteAt")
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link := NewDoublyLink[int]()
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err := link.DeleteAt(0)
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assert.IsNotNil(err)
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link.InsertAtTail(1)
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link.InsertAtTail(2)
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link.InsertAtTail(3)
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link.InsertAtTail(4)
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link.InsertAtTail(5)
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err = link.DeleteAt(5)
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assert.IsNotNil(err)
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err = link.DeleteAt(0)
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assert.IsNil(err)
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assert.Equal([]int{2, 3, 4, 5}, link.Values())
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link.DeleteAt(3)
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assert.Equal([]int{2, 3, 4}, link.Values())
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link.DeleteAt(1)
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assert.Equal(2, link.Size())
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assert.Equal([]int{2, 4}, link.Values())
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}
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func TestDoublyLink_Reverse(t *testing.T) {
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assert := internal.NewAssert(t, "TestDoublyLink_Reverse")
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link := NewDoublyLink[int]()
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link.InsertAtTail(1)
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link.InsertAtTail(2)
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link.InsertAtTail(3)
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link.InsertAtTail(4)
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link.Reverse()
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link.Print()
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assert.Equal([]int{4, 3, 2, 1}, link.Values())
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}
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func TestDoublyLink_GetMiddleNode(t *testing.T) {
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assert := internal.NewAssert(t, "TestDoublyLink_GetMiddleNode")
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link := NewDoublyLink[int]()
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link.InsertAtTail(1)
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link.InsertAtTail(2)
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link.InsertAtTail(3)
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link.InsertAtTail(4)
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middle1 := link.GetMiddleNode()
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assert.Equal(3, middle1.Value)
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link.InsertAtTail(5)
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link.InsertAtTail(6)
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link.InsertAtTail(7)
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middle2 := link.GetMiddleNode()
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assert.Equal(4, middle2.Value)
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}
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