feat(queue): implement queue in golang code

codes/go/chapter_stack_and_queue/array_queue.go

@@ -0,0 +1,92 @@
+// File: array_queue.go
+// Created Time: 2022-11-28
+// Author: Reanon ([email protected])
+
+package chapter_stack_and_queue
+
+import (
+	"fmt"
+	"strings"
+)
+
+// ArrayQueue 基于环形数组实现的队列, 不支持扩容
+type ArrayQueue struct {
+	data     []any // 用于存储队列元素的数组
+	capacity int   // 队列容量（即最多容量的元素个数）
+	head     int   // 头指针，指向队首
+	tail     int   // 尾指针，指向队尾 + 1
+}
+
+// NewArrayQueue 基于环形数组实现的队列
+func NewArrayQueue(capacity int) *ArrayQueue {
+	return &ArrayQueue{
+		data:     make([]any, capacity),
+		capacity: capacity,
+		head:     0,
+		tail:     0,
+	}
+}
+
+// Size 获取队列的长度
+func (q *ArrayQueue) Size() int {
+	size := (q.capacity + q.tail - q.head) % q.capacity
+	return size
+}
+
+// IsEmpty 判断队列是否为空
+func (q *ArrayQueue) IsEmpty() bool {
+	return q.tail-q.head == 0
+}
+
+// Offer 入队
+func (q *ArrayQueue) Offer(v any) {
+	// 当 tail == capacity 表示队列已满
+	if q.Size() == q.capacity {
+		return
+	}
+	// 尾结点后添加
+	q.data[q.tail] = v
+	// 尾指针向后移动一位，越过尾部后返回到数组头部
+	q.tail = (q.tail + 1) % q.capacity
+}
+
+// Poll 出队
+func (q *ArrayQueue) Poll() any {
+	if q.IsEmpty() {
+		return nil
+	}
+	v := q.data[q.head]
+	// 队头指针向后移动，越过尾部后返回到数组头部
+	q.head = (q.head + 1) % q.capacity
+	return v
+}
+
+// Peek 访问队首元素
+func (q *ArrayQueue) Peek() any {
+	if q.IsEmpty() {
+		return nil
+	}
+	v := q.data[q.head]
+	return v
+}
+
+func (q *ArrayQueue) Print() {
+	fmt.Println(q.toString())
+}
+
+// toString 通过字符串的方式输出
+func (q *ArrayQueue) toString() string {
+	// 为空时
+	if q.IsEmpty() {
+		return "empty items"
+	}
+	var builder strings.Builder
+	size := q.Size()
+	str := fmt.Sprintf("%+v", q.data[q.head])
+	for i := 1; i < size; i++ {
+		builder.WriteString(str + " -> ")
+		str = fmt.Sprintf("%+v", q.data[(i+q.head)%q.capacity])
+	}
+	builder.WriteString(str)
+	return builder.String()
+}

codes/go/chapter_stack_and_queue/linkedlist_queue.go

@@ -0,0 +1,79 @@
+// File: linkedlist_queue.go
+// Created Time: 2022-11-28
+// Author: Reanon ([email protected])
+
+package chapter_stack_and_queue
+
+import (
+	"container/list"
+	"fmt"
+	"strings"
+)
+
+// LinkedListQueue 基于链表实现的栈, 使用内置包 list 来实现栈
+type LinkedListQueue struct {
+	list *list.List
+}
+
+// NewLinkedListQueue 初始化链表
+func NewLinkedListQueue() *LinkedListQueue {
+	return &LinkedListQueue{
+		list: list.New(),
+	}
+}
+
+// Offer 入队
+func (s *LinkedListQueue) Offer(value any) {
+	s.list.PushBack(value)
+}
+
+// Poll 出队
+func (s *LinkedListQueue) Poll() any {
+	if s.IsEmpty() {
+		return nil
+	}
+	e := s.list.Front()
+	s.list.Remove(e)
+	return e.Value
+}
+
+// Peek 访问队首元素
+func (s *LinkedListQueue) Peek() any {
+	if s.IsEmpty() {
+		return nil
+	}
+	e := s.list.Front()
+	return e.Value
+}
+
+// Size 获取队列的长度
+func (s *LinkedListQueue) Size() int {
+	return s.list.Len()
+}
+
+// IsEmpty 判断队列是否为空
+func (s *LinkedListQueue) IsEmpty() bool {
+	return s.list.Len() == 0
+}
+
+func (s *LinkedListQueue) Print() {
+	fmt.Println(s.toString())
+}
+
+func (s *LinkedListQueue) toString() any {
+	var builder strings.Builder
+	if s.IsEmpty() {
+		fmt.Println("empty stack")
+		return nil
+	}
+	e := s.list.Front()
+	// 强转为 string, 会影响效率
+	str := fmt.Sprintf("%v", e.Value)
+	for e.Next() != nil {
+		builder.WriteString(str + " -> ")
+		e = e.Next()
+		str = fmt.Sprintf("%v", e.Value)
+	}
+	builder.WriteString(str)
+	return builder.String()
+}

codes/go/chapter_stack_and_queue/queue.go

@@ -0,0 +1,18 @@
+// File: queue.go
+// Created Time: 2022-11-29
+// Author: Reanon ([email protected])
+
+package chapter_stack_and_queue
+
+type Queue interface {
+	// Offer 元素入队
+	Offer(num int)
+	// Peek 访问首元素
+	Peek() int
+	// Poll 元素出队
+	Poll() int
+	// Size 获取队列长度
+	Size() int
+	// IsEmpty 队列是否为空
+	IsEmpty() bool
+}

codes/go/chapter_stack_and_queue/queue_test.go

@@ -0,0 +1,91 @@
+// File: queue_test.go
+// Created Time: 2022-11-28
+// Author: Reanon ([email protected])
+
+package chapter_stack_and_queue
+
+import "testing"
+
+func TestArrayQueue(t *testing.T) {
+	// 初始化队
+	capacity := 10
+	queue := NewArrayQueue(capacity)
+
+	// 元素入队
+	queue.Offer(1)
+	queue.Offer(2)
+	queue.Offer(3)
+	queue.Offer(4)
+	queue.Offer(5)
+	t.Log("队列 queue = ", queue.toString())
+
+	// 访问队首元素
+	peek := queue.Peek()
+	t.Log("队首元素 peek = ", peek)
+
+	// 元素出队
+	pop := queue.Poll()
+	t.Log("出队元素 pop  = ", pop, ", 出队后 queue =", queue.toString())
+
+	// 获取队的长度
+	size := queue.Size()
+	t.Log("队的长度 size = ", size)
+
+	// 判断是否为空
+	isEmpty := queue.IsEmpty()
+	t.Log("队是否为空 = ", isEmpty)
+}
+
+func TestLinkedListQueue(t *testing.T) {
+	// 初始化队
+	queue := NewLinkedListQueue()
+
+	// 元素入队
+	queue.Offer(1)
+	queue.Offer(2)
+	queue.Offer(3)
+	queue.Offer(4)
+	queue.Offer(5)
+	t.Log("队列 queue = ", queue.toString())
+
+	// 访问队首元素
+	peek := queue.Peek()
+	t.Log("队首元素 peek = ", peek)
+
+	// 元素出队
+	pop := queue.Poll()
+	t.Log("出队元素 pop  = ", pop, ", 出队后 queue =", queue.toString())
+
+	// 获取队的长度
+	size := queue.Size()
+	t.Log("队的长度 size = ", size)
+
+	// 判断是否为空
+	isEmpty := queue.IsEmpty()
+	t.Log("队是否为空 = ", isEmpty)
+}
+
+// BenchmarkArrayQueue 8 ns/op in Mac M1 Pro
+func BenchmarkArrayQueue(b *testing.B) {
+	capacity := 1000
+	stack := NewArrayQueue(capacity)
+	// use b.N for looping
+	for i := 0; i < b.N; i++ {
+		stack.Offer(777)
+	}
+	for i := 0; i < b.N; i++ {
+		stack.Poll()
+	}
+}
+
+// BenchmarkLinkedQueue 62.66 ns/op in Mac M1 Pro
+func BenchmarkLinkedQueue(b *testing.B) {
+	stack := NewLinkedListQueue()
+	// use b.N for looping
+	for i := 0; i < b.N; i++ {
+		stack.Offer(777)
+	}
+	for i := 0; i < b.N; i++ {
+		stack.Poll()
+	}
+}