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lib/inc/list/queue.h

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+#ifndef HW_LIB_QUEUE_H
+#define HW_LIB_QUEUE_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   双向链表节点结构体
+ */
+typedef struct DoublyListNode {
+    void *val;                     // 节点值
+    struct DoublyListNode *next;   // 后继节点
+    struct DoublyListNode *prev;   // 前驱节点
+} DoublyListNode;
+
+/**
+ * @brief   双端队列结构体
+ */
+typedef struct {
+    DoublyListNode *front, *rear;  // 头节点 front ，尾节点 rear
+    int queSize;                    // 双向队列的长度
+} LinkedListDeque;
+
+/**
+ * @brief   创建一个新的双端队列
+ * @return  LinkedListDeque*    返回新创建的双端队列指针
+ * @example deque = newLinkedListDeque();
+ */
+extern LinkedListDeque *newLinkedListDeque();
+
+/**
+ * @brief   销毁双端队列
+ * @param   deque: [输入]     双端队列指针
+ * @return  void
+ * @example delLinkedListdeque(deque);
+ */
+extern void delLinkedListdeque(LinkedListDeque *deque);
+
+/**
+ * @brief   获取队列大小
+ * @param   deque: [输入]     双端队列指针
+ * @return  int                返回队列中元素个数
+ * @example size = queue_size(deque);
+ */
+extern int queue_size(LinkedListDeque *deque);
+
+/**
+ * @brief   检查队列是否为空
+ * @param   deque: [输入]     双端队列指针
+ * @return  bool               若队列为空返回true，否则返回false
+ * @example if (queue_is_empty(deque)) { // do something }
+ */
+extern bool queue_is_empty(LinkedListDeque *deque);
+
+/**
+ * @brief   在队列头部插入元素
+ * @param   deque: [输入]     双端队列指针
+ * @param   data: [输入]      待插入的数据指针
+ * @return  void
+ * @example pushFirst(deque, newData);
+ */
+extern void pushFirst(LinkedListDeque *deque, void *data);
+
+/**
+ * @brief   在队列尾部插入元素
+ * @param   deque: [输入]     双端队列指针
+ * @param   data: [输入]      待插入的数据指针
+ * @return  void
+ * @example pushLast(deque, newData);
+ */
+extern void pushLast(LinkedListDeque *deque, void *data);
+
+/**
+ * @brief   获取队列头部元素但不移除
+ * @param   deque: [输入]     双端队列指针
+ * @return  void*              返回队列头部元素的指针，若队列为空返回NULL
+ * @example firstData = peekFirst(deque);
+ */
+extern void *peekFirst(LinkedListDeque *deque);
+
+/**
+ * @brief   获取队列尾部元素但不移除
+ * @param   deque: [输入]     双端队列指针
+ * @return  void*              返回队列尾部元素的指针，若队列为空返回NULL
+ * @example lastData = peekLast(deque);
+ */
+extern void *peekLast(LinkedListDeque *deque);
+
+/**
+ * @brief   弹出队列头部或尾部元素
+ * @param   deque: [输入]     双端队列指针
+ * @param   isFront: [输入]   若为true则从头部弹出，否则从尾部弹出
+ * @return  void*              返回被弹出元素的指针，若队列为空返回NULL
+ * @example poppedData = pop(deque, true);
+ */
+extern void *pop(LinkedListDeque *deque, bool isFront);
+
+/**
+ * @brief   弹出队列头部元素
+ * @param   deque: [输入]     双端队列指针
+ * @return  void*              返回被弹出的头部元素的指针，若队列为空返回NULL
+ * @example poppedData = popFirst(deque);
+ */
+extern void *popFirst(LinkedListDeque *deque);
+
+/**
+ * @brief   弹出队列尾部元素
+ * @param   deque: [输入]     双端队列指针
+ * @return  void*              返回被弹出的尾部元素的指针，若队列为空返回NULL
+ * @example poppedData = popLast(deque);
+ */
+extern void *popLast(LinkedListDeque *deque);
+
+
+#ifdef __cplusplus
+}
+#endif
+#endif //HW_LIB_QUEUE_H

lib/src/list/queue.cpp

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+#include <cstdlib>
+#include <cassert>
+#include "queue.h"
+
+
+DoublyListNode *newDoublyListNode(void *data) {
+    DoublyListNode *node = (DoublyListNode *) malloc(sizeof(DoublyListNode));
+    node->val = data;
+    node->next = NULL;
+    node->prev = NULL;
+    return node;
+}
+
+/* 析构函数 */
+void delDoublyListNode(DoublyListNode *node) {
+    free(node);
+}
+
+
+/* 构造函数 */
+LinkedListDeque *newLinkedListDeque() {
+    LinkedListDeque *deque = (LinkedListDeque *) malloc(sizeof(LinkedListDeque));
+    deque->front = NULL;
+    deque->rear = NULL;
+    deque->queSize = 0;
+    return deque;
+}
+
+/* 析构函数 */
+void delLinkedListdeque(LinkedListDeque *deque) {
+    // 释放所有节点
+    for (int i = 0; i < deque->queSize && deque->front != NULL; i++) {
+        DoublyListNode *tmp = deque->front;
+        deque->front = deque->front->next;
+        free(tmp);
+    }
+    // 释放 deque 结构体
+    free(deque);
+}
+
+/* 获取队列的长度 */
+int queue_size(LinkedListDeque *deque) {
+    return deque->queSize;
+}
+
+/* 判断队列是否为空 */
+bool queue_is_empty(LinkedListDeque *deque) {
+    return (queue_size(deque) == 0);
+}
+
+/* 入队 */
+void push(LinkedListDeque *deque, void *data, bool isFront) {
+    DoublyListNode *node = newDoublyListNode(data);
+    // 若链表为空，则令 front 和 rear 都指向node
+    if (queue_is_empty(deque)) {
+        deque->front = deque->rear = node;
+    }
+        // 队首入队操作
+    else if (isFront) {
+        // 将 node 添加至链表头部
+        deque->front->prev = node;
+        node->next = deque->front;
+        deque->front = node; // 更新头节点
+    }
+        // 队尾入队操作
+    else {
+        // 将 node 添加至链表尾部
+        deque->rear->next = node;
+        node->prev = deque->rear;
+        deque->rear = node;
+    }
+    deque->queSize++; // 更新队列长度
+}
+
+/* 队首入队 */
+void pushFirst(LinkedListDeque *deque, void *data) {
+    push(deque, data, true);
+}
+
+/* 队尾入队 */
+void pushLast(LinkedListDeque *deque, void *data) {
+    push(deque, data, false);
+}
+
+/* 访问队首元素 */
+void *peekFirst(LinkedListDeque *deque) {
+    assert(queue_size(deque) && deque->front);
+    return deque->front->val;
+}
+
+/* 访问队尾元素 */
+void *peekLast(LinkedListDeque *deque) {
+    assert(queue_size(deque) && deque->rear);
+    return deque->rear->val;
+}
+
+/* 出队 */
+void *pop(LinkedListDeque *deque, bool isFront) {
+    if (queue_is_empty(deque))
+        return nullptr;
+    void *val;
+    // 队首出队操作
+    if (isFront) {
+        val = peekFirst(deque); // 暂存头节点值
+        DoublyListNode *fNext = deque->front->next;
+        if (fNext) {
+            fNext->prev = NULL;
+            deque->front->next = NULL;
+        }
+        delDoublyListNode(deque->front);
+        deque->front = fNext; // 更新头节点
+    }
+        // 队尾出队操作
+    else {
+        val = peekLast(deque); // 暂存尾节点值
+        DoublyListNode *rPrev = deque->rear->prev;
+        if (rPrev) {
+            rPrev->next = NULL;
+            deque->rear->prev = NULL;
+        }
+        delDoublyListNode(deque->rear);
+        deque->rear = rPrev; // 更新尾节点
+    }
+    deque->queSize--; // 更新队列长度
+    return val;
+}
+
+/* 队首出队 */
+void *popFirst(LinkedListDeque *deque) {
+    return pop(deque, true);
+}
+
+/* 队尾出队 */
+void *popLast(LinkedListDeque *deque) {
+    return pop(deque, false);
+}