Update stack and queue.

codes/cpp/chapter_stack_and_queue/array_queue.cpp

@@ -6,3 +6,119 @@
 
 #include "../include/include.hpp"
 
+/* 基于环形数组实现的队列 */
+class ArrayQueue {
+private:
+    vector<int> nums; // 用于存储队列元素的数组
+    int front = 0;    // 头指针，指向队首
+    int rear = 0;     // 尾指针，指向队尾 + 1
+
+public:
+    ArrayQueue(int capacity) {
+        // 初始化数组
+        nums.resize(capacity);
+    }
+
+    /* 获取队列的容量 */
+    int capacity() {
+        return nums.size();
+    }
+
+    /* 获取队列的长度 */
+    int size() {
+        int cap = capacity();
+        // 由于将数组看作为环形，可能 rear < front ，因此需要取余数
+        return (cap + rear - front) % cap;
+    }
+
+    /* 判断队列是否为空 */
+    bool empty() {
+        return rear - front == 0;
+    }
+
+    /* 入队 */
+    void offer(int num) {
+        if (size() == capacity()) {
+            cout << "队列已满" << endl;
+            return;
+        }
+        // 尾结点后添加 num
+        nums[rear] = num;
+        // 尾指针向后移动一位，越过尾部后返回到数组头部
+        rear = (rear + 1) % capacity();
+    }
+
+    /* 出队 */
+    int poll() {
+        // 删除头结点
+        if (empty())
+            throw out_of_range("队列为空");
+        int num = nums[front];
+        // 队头指针向后移动，越过尾部后返回到数组头部
+        front = (front + 1) % capacity();
+        return num;
+    }
+
+    /* 访问队首元素 */
+    int peek() {
+        // 删除头结点
+        if (empty())
+            throw out_of_range("队列为空");
+        return nums[front];
+    }
+
+    vector<int> toVector() {
+        int siz = size();
+        int cap = capacity();
+        // 仅转换有效长度范围内的列表元素
+        vector<int> arr(siz);
+        for (int i = 0, j = front; i < siz; i++, j++) {
+            arr[i] = nums[j % cap];
+        }
+        return arr;
+    }
+};
+
+
+/* Driver Code */
+int main() {
+    /* 初始化队列 */
+    int capacity = 10;
+    ArrayQueue* queue = new ArrayQueue(capacity);
+
+    /* 元素入队 */
+    queue->offer(1);
+    queue->offer(3);
+    queue->offer(2);
+    queue->offer(5);
+    queue->offer(4);
+    cout << "队列 queue = ";
+    PrintUtil::printVector(queue->toVector());
+
+    /* 访问队首元素 */
+    int peek = queue->peek();
+    cout << "队首元素 peek = " << peek << endl;
+
+    /* 元素出队 */
+    int poll = queue->poll();
+    cout << "出队元素 poll = " << poll << "，出队后 queue = ";
+    PrintUtil::printVector(queue->toVector());
+
+    /* 获取队列的长度 */
+    int size = queue->size();
+    cout << "队列长度 size = " << size << endl;
+
+    /* 判断队列是否为空 */
+    bool empty = queue->empty();
+    cout << "队列是否为空 = " << empty << endl;
+
+    /* 测试环形数组 */
+    for (int i = 0; i < 10; i++) {
+        queue->offer(i);
+        queue->poll();
+        cout << "第 " << i << " 轮入队 + 出队后 queue = ";
+        PrintUtil::printVector(queue->toVector());
+    }
+
+    return 0;
+}