refactor: reconstructure souce file into the corresponding folder

datastructure/link/singlylink.go

@@ -0,0 +1,224 @@
+package datastructure
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/duke-git/lancet/datastructure"
+)
+
+// SinglyLink is a linked list. Whose node has a Value generics and Next pointer points to a next node of the link.
+type SinglyLink[T any] struct {
+	Head   *datastructure.LinkNode[T]
+	length int
+}
+
+// NewSinglyLink return *SinglyLink instance
+func NewSinglyLink[T any]() *SinglyLink[T] {
+	return &SinglyLink[T]{Head: nil}
+}
+
+// InsertAtHead insert value into singly linklist at head index
+func (link *SinglyLink[T]) InsertAtHead(value T) {
+	newNode := datastructure.NewLinkNode(value)
+	newNode.Next = link.Head
+	link.Head = newNode
+	link.length++
+}
+
+// InsertAtTail insert value into singly linklist at tail index
+func (link *SinglyLink[T]) InsertAtTail(value T) {
+	current := link.Head
+	if current == nil {
+		link.InsertAtHead(value)
+		return
+	}
+
+	for current.Next != nil {
+		current = current.Next
+	}
+
+	newNode := datastructure.NewLinkNode(value)
+	newNode.Next = nil
+	current.Next = newNode
+
+	link.length++
+}
+
+// InsertAt insert value into singly linklist at index
+func (link *SinglyLink[T]) InsertAt(index int, value T) error {
+	size := link.length
+	if index < 0 || index > size {
+		return errors.New("param index should between 0 and the length of singly link.")
+	}
+
+	if index == 0 {
+		link.InsertAtHead(value)
+		return nil
+	}
+
+	if index == size {
+		link.InsertAtTail(value)
+		return nil
+	}
+
+	i := 0
+	current := link.Head
+
+	for current != nil {
+		if i == index-1 {
+			newNode := datastructure.NewLinkNode(value)
+			newNode.Next = current.Next
+			current.Next = newNode
+			link.length++
+
+			return nil
+		}
+		i++
+		current = current.Next
+	}
+
+	return errors.New("singly link list no exist")
+}
+
+// DeleteAtHead delete value in singly linklist at head index
+func (link *SinglyLink[T]) DeleteAtHead() error {
+	if link.Head == nil {
+		return errors.New("singly link list no exist")
+	}
+	current := link.Head
+	link.Head = current.Next
+	link.length--
+
+	return nil
+}
+
+// DeleteAtTail delete value in singly linklist at tail index
+func (link *SinglyLink[T]) DeleteAtTail() error {
+	if link.Head == nil {
+		return errors.New("singly link list no exist")
+	}
+	current := link.Head
+	if current.Next == nil {
+		return link.DeleteAtHead()
+	}
+
+	for current.Next.Next != nil {
+		current = current.Next
+	}
+
+	current.Next = nil
+	link.length--
+	return nil
+}
+
+// DeleteAt delete value in singly linklist at index
+func (link *SinglyLink[T]) DeleteAt(index int) error {
+	if link.Head == nil {
+		return errors.New("singly link list no exist")
+	}
+	current := link.Head
+	if current.Next == nil || index == 0 {
+		return link.DeleteAtHead()
+	}
+
+	if index == link.length-1 {
+		return link.DeleteAtTail()
+	}
+
+	if index < 0 || index > link.length-1 {
+		return errors.New("param index should between 0 and link size -1.")
+	}
+
+	i := 0
+	for current != nil {
+		if i == index-1 {
+			current.Next = current.Next.Next
+			link.length--
+			return nil
+		}
+		i++
+		current = current.Next
+	}
+
+	return errors.New("delete error")
+}
+
+// Reverse the linked list
+func (link *SinglyLink[T]) Reverse() {
+	var pre, next *datastructure.LinkNode[T]
+
+	current := link.Head
+
+	for current != nil {
+		next = current.Next
+		current.Next = pre
+		pre = current
+		current = next
+	}
+
+	link.Head = pre
+}
+
+// GetMiddleNode return node at middle index of linked list
+func (link *SinglyLink[T]) GetMiddleNode() *datastructure.LinkNode[T] {
+	if link.Head == nil {
+		return nil
+	}
+	if link.Head.Next == nil {
+		return link.Head
+	}
+	fast := link.Head
+	slow := link.Head
+
+	for fast != nil {
+		fast = fast.Next
+
+		if fast != nil {
+			fast = fast.Next
+			slow = slow.Next
+		} else {
+			return slow
+		}
+	}
+	return slow
+}
+
+// Size return the count of singly linked list
+func (link *SinglyLink[T]) Size() int {
+	return link.length
+}
+
+// Values return slice of all singly linklist node value
+func (link *SinglyLink[T]) Values() []T {
+	res := []T{}
+	current := link.Head
+	for current != nil {
+		res = append(res, current.Value)
+		current = current.Next
+	}
+	return res
+}
+
+// IsEmpty checks if link is empty or not
+func (link *SinglyLink[T]) IsEmpty() bool {
+	return link.length == 0
+}
+
+// IsEmpty checks if link is empty or not
+func (link *SinglyLink[T]) Clear() {
+	link.Head = nil
+	link.length = 0
+}
+
+// Print all nodes info of a linked list
+func (link *SinglyLink[T]) Print() {
+	current := link.Head
+	info := "[ "
+	for current != nil {
+		info += fmt.Sprintf("%+v, ", current)
+		current = current.Next
+	}
+	info += " ]"
+	fmt.Println(info)
+}