feat: add DeleteAtHead, DeleteAtTail, DeleteAt, Reverse, Size, GetMiddleNode funcs in singlelink

datastructure/singlylink.go

@@ -16,29 +16,6 @@ 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)
@@ -99,5 +76,136 @@ func (link *SinglyLink[T]) InsertAt(index int, value T) error {
 		current = current.Next
 	}
 
-	return errors.New("singly link no exist")
+	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 *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() *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
+}
+
+// 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)
 }

datastructure/singlylink_test.go

@@ -60,3 +60,106 @@ func TestSinglyLink_InsertAt(t *testing.T) {
 	assert.Equal(expected, values)
 
 }
+
+func TestSinglyLink_DeleteAtHead(t *testing.T) {
+	assert := internal.NewAssert(t, "TestSinglyLink_DeleteAtHead")
+
+	link := NewSinglyLink[int]()
+	err := link.DeleteAtHead()
+	assert.IsNotNil(err)
+
+	link.InsertAtTail(1)
+	link.InsertAtTail(2)
+	link.InsertAtTail(3)
+	link.InsertAtTail(4)
+
+	link.DeleteAtHead()
+	link.Print()
+
+	expected := []int{2, 3, 4}
+	values := link.Values()
+
+	assert.Equal(expected, values)
+}
+
+func TestSinglyLink_DeleteAtTail(t *testing.T) {
+	assert := internal.NewAssert(t, "TestSinglyLink_DeleteAtTail")
+
+	link := NewSinglyLink[int]()
+	err := link.DeleteAtTail()
+	assert.IsNotNil(err)
+
+	link.InsertAtTail(1)
+	link.InsertAtTail(2)
+	link.InsertAtTail(3)
+	link.InsertAtTail(4)
+
+	link.DeleteAtTail()
+	link.Print()
+
+	expected := []int{1, 2, 3}
+	values := link.Values()
+
+	assert.Equal(expected, values)
+}
+
+func TestSinglyLink_DeleteAt(t *testing.T) {
+	assert := internal.NewAssert(t, "TestSinglyLink_DeleteAt")
+
+	link := NewSinglyLink[int]()
+	err := link.DeleteAt(0)
+	assert.IsNotNil(err)
+
+	link.InsertAtTail(1)
+	link.InsertAtTail(2)
+	link.InsertAtTail(3)
+	link.InsertAtTail(4)
+	link.InsertAtTail(5)
+
+	err = link.DeleteAt(5)
+	assert.IsNotNil(err)
+
+	err = link.DeleteAt(0)
+	assert.IsNil(err)
+	assert.Equal([]int{2, 3, 4, 5}, link.Values())
+
+	link.DeleteAt(3)
+	assert.Equal([]int{2, 3, 4}, link.Values())
+
+	link.DeleteAt(1)
+	assert.Equal(2, link.Size())
+	assert.Equal([]int{2, 4}, link.Values())
+}
+
+func TestSinglyLink_Reverse(t *testing.T) {
+	assert := internal.NewAssert(t, "TestSinglyLink_Reverse")
+
+	link := NewSinglyLink[int]()
+	link.InsertAtTail(1)
+	link.InsertAtTail(2)
+	link.InsertAtTail(3)
+	link.InsertAtTail(4)
+
+	link.Reverse()
+	link.Print()
+	assert.Equal([]int{4, 3, 2, 1}, link.Values())
+}
+
+func TestSinglyLink_GetMiddleNode(t *testing.T) {
+	assert := internal.NewAssert(t, "TestSinglyLink_GetMiddleNode")
+
+	link := NewSinglyLink[int]()
+	link.InsertAtTail(1)
+	link.InsertAtTail(2)
+	link.InsertAtTail(3)
+	link.InsertAtTail(4)
+
+	middle1 := link.GetMiddleNode()
+	assert.Equal(3, middle1.Value)
+
+	link.InsertAtTail(5)
+	link.InsertAtTail(6)
+	link.InsertAtTail(7)
+	middle2 := link.GetMiddleNode()
+	assert.Equal(4, middle2.Value)
+}