Add the initial EN translation for C++ code (#1346)

en/codes/cpp/chapter_stack_and_queue/array_queue.cpp

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+/**
+ * File: array_queue.cpp
+ * Created Time: 2022-11-25
+ * Author: krahets (krahets@163.com)
+ */
+
+#include "../utils/common.hpp"
+
+/* Queue class based on circular array */
+class ArrayQueue {
+  private:
+    int *nums;       // Array for storing queue elements
+    int front;       // Front pointer, pointing to the front element
+    int queSize;     // Queue length
+    int queCapacity; // Queue capacity
+
+  public:
+    ArrayQueue(int capacity) {
+        // Initialize an array
+        nums = new int[capacity];
+        queCapacity = capacity;
+        front = queSize = 0;
+    }
+
+    ~ArrayQueue() {
+        delete[] nums;
+    }
+
+    /* Get the capacity of the queue */
+    int capacity() {
+        return queCapacity;
+    }
+
+    /* Get the length of the queue */
+    int size() {
+        return queSize;
+    }
+
+    /* Determine if the queue is empty */
+    bool isEmpty() {
+        return size() == 0;
+    }
+
+    /* Enqueue */
+    void push(int num) {
+        if (queSize == queCapacity) {
+            cout << "Queue is full" << endl;
+            return;
+        }
+        // Calculate rear pointer, pointing to rear index + 1
+        // Use modulo operation to wrap the rear pointer from the end of the array back to the start
+        int rear = (front + queSize) % queCapacity;
+        // Add num to the rear
+        nums[rear] = num;
+        queSize++;
+    }
+
+    /* Dequeue */
+    int pop() {
+        int num = peek();
+        // Move front pointer one position backward, returning to the head of the array if it exceeds the tail
+        front = (front + 1) % queCapacity;
+        queSize--;
+        return num;
+    }
+
+    /* Access front element */
+    int peek() {
+        if (isEmpty())
+            throw out_of_range("Queue is empty");
+        return nums[front];
+    }
+
+    /* Convert array to Vector and return */
+    vector<int> toVector() {
+        // Only convert elements within valid length range
+        vector<int> arr(queSize);
+        for (int i = 0, j = front; i < queSize; i++, j++) {
+            arr[i] = nums[j % queCapacity];
+        }
+        return arr;
+    }
+};
+
+/* Driver Code */
+int main() {
+    /* Initialize queue */
+    int capacity = 10;
+    ArrayQueue *queue = new ArrayQueue(capacity);
+
+    /* Element enqueue */
+    queue->push(1);
+    queue->push(3);
+    queue->push(2);
+    queue->push(5);
+    queue->push(4);
+    cout << "Queue queue = ";
+    printVector(queue->toVector());
+
+    /* Access front element */
+    int peek = queue->peek();
+    cout << "Front element peek = " << peek << endl;
+
+    /* Element dequeue */
+    peek = queue->pop();
+    cout << "Element dequeued = " << peek << ", after dequeuing";
+    printVector(queue->toVector());
+
+    /* Get the length of the queue */
+    int size = queue->size();
+    cout << "Length of the queue size = " << size << endl;
+
+    /* Determine if the queue is empty */
+    bool empty = queue->isEmpty();
+    cout << "Is the queue empty = " << empty << endl;
+
+    /* Test circular array */
+    for (int i = 0; i < 10; i++) {
+        queue->push(i);
+        queue->pop();
+        cout << "After the " << i << "th round of enqueueing + dequeuing, queue = ";
+        printVector(queue->toVector());
+    }
+
+    // Free memory
+    delete queue;
+
+    return 0;
+}