feat: add some functons of singlelink

datastructure/linknode.go

@@ -0,0 +1,13 @@
+package datastructure
+
+// LinkNode is a linkedlist node, which have a value and Pre points to previous node, Next points to a next node of the link.
+type LinkNode[T any] struct {
+	Value T
+	Pre   *LinkNode[T]
+	Next  *LinkNode[T]
+}
+
+func NewLinkNode[T any](value T) *LinkNode[T] {
+	return &LinkNode[T]{value, nil, nil}
+}
+

datastructure/singlylink.go

@@ -1,12 +1,103 @@
 package datastructure
 
-// Node is a linkedlist node, which have a value and Pre points to previous node, Next points to a next node of the link.
-type Node[T any] struct {
-	Value T
-	Pre   *Node[T]
-	Next  *Node[T]
+import (
+	"errors"
+	"fmt"
+)
+
+// SinglyLink is a linkedlist of node, which have a value and Pre points to previous node, Next points to a next node of the link.
+type SinglyLink[T any] struct {
+	Head   *LinkNode[T]
+	length int
 }
 
-func NewNode[T any](value T) *Node[T] {
-	return &Node[T]{value, nil, nil}
+// NewSinglyLink return *SinglyLink instance
+func NewSinglyLink[T any]() *SinglyLink[T] {
+	return &SinglyLink[T]{Head: nil}
+}
+
+// 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
+}
+
+// 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)
+}
+
+// InsertAtHead insert value into singly linklist at head index
+func (link *SinglyLink[T]) InsertAtHead(value T) {
+	newNode := 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 := 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 := NewLinkNode(value)
+			newNode.Next = current.Next
+			current.Next = newNode
+			link.length++
+
+			return nil
+		}
+		i++
+		current = current.Next
+	}
+
+	return errors.New("singly link no exist")
 }

datastructure/singlylink_test.go

@@ -0,0 +1,62 @@
+package datastructure
+
+import (
+	"testing"
+
+	"github.com/duke-git/lancet/internal"
+)
+
+func TestSinglyLink_InsertAtFirst(t *testing.T) {
+	assert := internal.NewAssert(t, "TestSinglyLink_InsertAtFirst")
+
+	link := NewSinglyLink[int]()
+	link.InsertAtHead(1)
+	link.InsertAtHead(2)
+	link.InsertAtHead(3)
+	link.Print()
+
+	expected := []int{3, 2, 1}
+	values := link.Values()
+
+	assert.Equal(expected, values)
+}
+
+func TestSinglyLink_InsertAtTail(t *testing.T) {
+	assert := internal.NewAssert(t, "TestSinglyLink_InsertAtTail")
+
+	link := NewSinglyLink[int]()
+	link.InsertAtTail(1)
+	link.InsertAtTail(2)
+	link.InsertAtTail(3)
+	link.Print()
+
+	expected := []int{1, 2, 3}
+	values := link.Values()
+
+	assert.Equal(expected, values)
+}
+
+func TestSinglyLink_InsertAt(t *testing.T) {
+	assert := internal.NewAssert(t, "TestSinglyLink_InsertAt")
+
+	link := NewSinglyLink[int]()
+
+	err := link.InsertAt(1, 1)
+	assert.IsNotNil(err)
+
+	err = link.InsertAt(0, 1)
+	err = link.InsertAt(1, 2)
+	err = link.InsertAt(2, 4)
+	err = link.InsertAt(2, 3)
+
+	if err != nil {
+		t.FailNow()
+	}
+	link.Print()
+
+	expected := []int{1, 2, 3, 4}
+	values := link.Values()
+
+	assert.Equal(expected, values)
+
+}