From a554590fa81b75ce156121aae74619d1a998d430 Mon Sep 17 00:00:00 2001
From: reanon <793584285@qq.com>
Date: Tue, 29 Nov 2022 10:43:47 +0800
Subject: [PATCH] feat(deque): add implementation of deque

---
 .../go/chapter_stack_and_queue/deque_test.go  |  53 +++++++++
 .../linkedlist_deque.go                       | 102 ++++++++++++++++++
 .../go/chapter_stack_and_queue/queue_test.go  |   1 -
 3 files changed, 155 insertions(+), 1 deletion(-)
 create mode 100644 codes/go/chapter_stack_and_queue/deque_test.go
 create mode 100644 codes/go/chapter_stack_and_queue/linkedlist_deque.go

diff --git a/codes/go/chapter_stack_and_queue/deque_test.go b/codes/go/chapter_stack_and_queue/deque_test.go
new file mode 100644
index 0000000..c0eaf08
--- /dev/null
+++ b/codes/go/chapter_stack_and_queue/deque_test.go
@@ -0,0 +1,53 @@
+// File: deque_test.go
+// Created Time: 2022-11-29
+// Author: Reanon (793584285@qq.com)
+
+package chapter_stack_and_queue
+
+import "testing"
+
+func TestLinkedListDeque(t *testing.T) {
+	// 初始化队列
+	var deque Deque
+	deque = NewLinkedListDeque()
+
+	// 元素入队
+	deque.OfferLast(2)
+	deque.OfferLast(5)
+	deque.OfferLast(4)
+	deque.OfferFirst(3)
+	deque.OfferFirst(1)
+	t.Log("队列 deque = ", deque.toString())
+
+	// 访问队首元素
+	peekFirst := deque.PeekFirst()
+	t.Log("队首元素 peek = ", peekFirst)
+	peekLast := deque.PeekLast()
+	t.Log("队尾元素 peek = ", peekLast)
+
+	// 元素出队
+	pollFirst := deque.PollFirst()
+	t.Log("队首出队元素 pollFirst = ", pollFirst, "，队首出队后 deque = ", deque.toString())
+	pollLast := deque.PollLast()
+	t.Log("队尾出队元素 pollLast  = ", pollLast, "，队尾出队后 deque = ", deque.toString())
+
+	// 获取队的长度
+	size := deque.Size()
+	t.Log("队的长度 size = ", size)
+
+	// 判断是否为空
+	isEmpty := deque.IsEmpty()
+	t.Log("队是否为空 = ", isEmpty)
+}
+
+// BenchmarkArrayQueue 67.92 ns/op in Mac M1 Pro
+func BenchmarkLinkedListDeque(b *testing.B) {
+	stack := NewLinkedListDeque()
+	// use b.N for looping
+	for i := 0; i < b.N; i++ {
+		stack.OfferLast(777)
+	}
+	for i := 0; i < b.N; i++ {
+		stack.PollFirst()
+	}
+}
diff --git a/codes/go/chapter_stack_and_queue/linkedlist_deque.go b/codes/go/chapter_stack_and_queue/linkedlist_deque.go
new file mode 100644
index 0000000..62a6149
--- /dev/null
+++ b/codes/go/chapter_stack_and_queue/linkedlist_deque.go
@@ -0,0 +1,102 @@
+// File: linkedlist_deque.go
+// Created Time: 2022-11-29
+// Author: Reanon (793584285@qq.com)
+
+package chapter_stack_and_queue
+
+import (
+	"container/list"
+	"fmt"
+	"strings"
+)
+
+// LinkedListDeque 基于链表实现的双端队列, 使用内置包 list 来实现栈
+type LinkedListDeque struct {
+	list *list.List
+}
+
+// NewLinkedListDeque 初始化双端队列
+func NewLinkedListDeque() *LinkedListDeque {
+	return &LinkedListDeque{
+		list: list.New(),
+	}
+}
+
+// OfferFirst 元素入队
+func (s *LinkedListDeque) OfferFirst(value any) {
+	s.list.PushFront(value)
+}
+
+// OfferLast 元素入队
+func (s *LinkedListDeque) OfferLast(value any) {
+	s.list.PushBack(value)
+}
+
+// PollFirst 元素出队
+func (s *LinkedListDeque) PollFirst() any {
+	if s.IsEmpty() {
+		return nil
+	}
+	e := s.list.Front()
+	s.list.Remove(e)
+	return e.Value
+}
+
+// PollLast 元素出队
+func (s *LinkedListDeque) PollLast() any {
+	if s.IsEmpty() {
+		return nil
+	}
+	e := s.list.Back()
+	s.list.Remove(e)
+	return e.Value
+}
+
+// PeekFirst 访问首元素
+func (s *LinkedListDeque) PeekFirst() any {
+	if s.IsEmpty() {
+		return nil
+	}
+	e := s.list.Front()
+	return e.Value
+}
+
+// PeekLast 访问尾元素
+func (s *LinkedListDeque) PeekLast() any {
+	if s.IsEmpty() {
+		return nil
+	}
+	e := s.list.Back()
+	return e.Value
+}
+
+// Size 获取队列的长度
+func (s *LinkedListDeque) Size() int {
+	return s.list.Len()
+}
+
+// IsEmpty 判断队列是否为空
+func (s *LinkedListDeque) IsEmpty() bool {
+	return s.list.Len() == 0
+}
+
+func (s *LinkedListDeque) Print() {
+	fmt.Println(s.toString())
+}
+
+func (s *LinkedListDeque) toString() string {
+	var builder strings.Builder
+	if s.IsEmpty() {
+		fmt.Println("empty stack")
+	}
+	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()
+}
diff --git a/codes/go/chapter_stack_and_queue/queue_test.go b/codes/go/chapter_stack_and_queue/queue_test.go
index 996b0bc..e8c74ec 100644
--- a/codes/go/chapter_stack_and_queue/queue_test.go
+++ b/codes/go/chapter_stack_and_queue/queue_test.go
@@ -7,7 +7,6 @@ package chapter_stack_and_queue
 import "testing"
 
 func TestArrayQueue(t *testing.T) {
-
 	// 初始化队列，使用队列的通用接口
 	var queue Queue
 	capacity := 10