From 39e508b3838b88047fa327778847729c57bd52ce Mon Sep 17 00:00:00 2001
From: S-N-O-R-L-A-X <S-N-O-R-L-A-X@users.noreply.github.com>
Date: Tue, 13 Dec 2022 00:00:06 +0800
Subject: [PATCH] feat: add array_queue in js

---
 .../chapter_stack_and_queue/array_queue.js    | 123 ++++++++++++++++++
 .../chapter_stack_and_queue/array_queue.ts    |   2 +
 2 files changed, 125 insertions(+)
 create mode 100644 codes/javascript/chapter_stack_and_queue/array_queue.js

diff --git a/codes/javascript/chapter_stack_and_queue/array_queue.js b/codes/javascript/chapter_stack_and_queue/array_queue.js
new file mode 100644
index 0000000..fa84fce
--- /dev/null
+++ b/codes/javascript/chapter_stack_and_queue/array_queue.js
@@ -0,0 +1,123 @@
+/**
+ * File: array_queue.js
+ * Created Time: 2022-12-13
+ * Author: S-N-O-R-L-A-X (snorlax.xu@outlook.com)
+ */
+
+
+/* 基于环形数组实现的队列 */
+class ArrayQueue {
+    queue;     // 用于存储队列元素的数组
+    front = 0;  // 头指针，指向队首
+    rear = 0;   // 尾指针，指向队尾 + 1
+    CAPACITY = 1e5;
+
+    constructor(capacity) {
+        this.queue = new Array(capacity ?? this.CAPACITY);
+    }
+
+    /* 获取队列的容量 */
+    get capacity() {
+        return this.queue.length;
+    }
+
+    /* 获取队列的长度 */
+    get size() {
+        // 由于将数组看作为环形，可能 rear < front ，因此需要取余数
+        return (this.capacity + this.rear - this.front) % this.capacity;
+    }
+
+    /* 判断队列是否为空 */
+    empty() {
+        return this.rear - this.front == 0;
+    }
+
+    /* 入队 */
+    offer(num) {
+        if (this.size == this.capacity) {
+            console.log("队列已满");
+            return;
+        }
+        // 尾结点后添加 num
+        this.queue[this.rear] = num;
+        // 尾指针向后移动一位，越过尾部后返回到数组头部
+        this.rear = (this.rear + 1) % this.capacity;
+    }
+
+    /* 出队 */
+    poll() {
+        const num = this.peek();
+        // 队头指针向后移动一位，若越过尾部则返回到数组头部
+        this.front = (this.front + 1) % this.capacity;
+        return num;
+    }
+
+    /* 访问队首元素 */
+    peek() {
+        // 删除头结点
+        if (this.empty())
+            throw new Error("The queue is empty!");
+        return this.queue[this.front];
+    }
+
+    /* 访问指定索引元素 */
+    get(index) {
+        if (index >= this.size)
+            throw new Error("Index out of bounds!");
+        return this.queue[(this.front + index) % this.capacity];
+    }
+
+    /* 返回 Array */
+    toArray() {
+        const siz = this.size;
+        const cap = this.capacity;
+        // 仅转换有效长度范围内的列表元素
+        const arr = new Array(siz);
+        for (let i = 0, j = this.front; i < siz; i++, j++) {
+            arr[i] = this.queue[j % cap];
+        }
+        return arr;
+    }
+}
+
+/* 初始化队列 */
+const capacity = 10;
+const queue = new ArrayQueue(capacity);
+
+/* 元素入队 */
+queue.offer(1);
+queue.offer(3);
+queue.offer(2);
+queue.offer(5);
+queue.offer(4);
+console.log("队列 queue = ");
+console.log(queue.toArray());
+
+/* 访问队首元素 */
+const peek = queue.peek();
+console.log("队首元素 peek = " + peek);
+
+/* 访问指定索引元素 */
+const num = queue.get(2);
+console.log("队列第 3 个元素为 num = " + num);
+
+/* 元素出队 */
+const poll = queue.poll();
+console.log("出队元素 poll = " + poll + "，出队后 queue = ");
+console.log(queue.toArray());
+
+/* 获取队列的长度 */
+const size = queue.size;
+console.log("队列长度 size = " + size);
+
+/* 判断队列是否为空 */
+const empty = queue.empty();
+console.log("队列是否为空 = " + empty);
+
+/* 测试环形数组 */
+for (let i = 0; i < 10; i++) {
+    queue.offer(i);
+    queue.poll();
+    console.log("第 " + i + " 轮入队 + 出队后 queue = ");
+    console.log(queue.toArray());
+}
diff --git a/codes/typescript/chapter_stack_and_queue/array_queue.ts b/codes/typescript/chapter_stack_and_queue/array_queue.ts
index c232335..789d2d9 100644
--- a/codes/typescript/chapter_stack_and_queue/array_queue.ts
+++ b/codes/typescript/chapter_stack_and_queue/array_queue.ts
@@ -121,3 +121,5 @@ for (let i = 0; i < 10; i++) {
     console.log("第 " + i + " 轮入队 + 出队后 queue = ");
     console.log(queue.toArray());
 }
+
+export { };
\ No newline at end of file