Lecture 256:- Let's Code Circular Queue

Here's a C++ implementation of a Circular Queue:

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#include <iostream> const int MAX_SIZE = 5; class CircularQueue { private:    int arr[MAX_SIZE];    int frontIdx;    int rearIdx; public:    CircularQueue() {        frontIdx = -1;        rearIdx = -1;    }    bool isEmpty() {        return frontIdx == -1 && rearIdx == -1;    }    bool isFull() {        return (rearIdx + 1) % MAX_SIZE == frontIdx || (frontIdx == 0 && rearIdx == MAX_SIZE - 1);    }    void enqueue(int element) {        if (isFull()) {            std::cout << "Queue is full. Cannot enqueue." << std::endl;            return;        }        if (isEmpty()) {            frontIdx = 0;        }        rearIdx = (rearIdx + 1) % MAX_SIZE;        arr[rearIdx] = element;    }    void dequeue() {        if (isEmpty()) {            std::cout << "Queue is empty. Cannot dequeue." << std::endl;            return;        }        if (frontIdx == rearIdx) {            frontIdx = -1;            rearIdx = -1;        } else {            frontIdx = (frontIdx + 1) % MAX_SIZE;        }    }    int front() {        if (isEmpty()) {            std::cout << "Queue is empty." << std::endl;            return -1; // Assuming -1 is not a valid element in the queue.        }        return arr[frontIdx];    }    int size() {        if (isEmpty()) {            return 0;        }        return (rearIdx >= frontIdx) ? (rearIdx - frontIdx + 1) : (MAX_SIZE - frontIdx + rearIdx + 1);    } }; int main() {    CircularQueue queue;    queue.enqueue(10);    queue.enqueue(20);    queue.enqueue(30);    std::cout << "Front element: " << queue.front() << std::endl;    queue.dequeue();    std::cout << "Front element after dequeue: " << queue.front() << std::endl;    std::cout << "Queue size: " << queue.size() << std::endl;    return 0; }

In this implementation, we use an array to store the elements of the circular queue. The frontIdx and rearIdx pointers wrap around the array in a circular fashion using the modulo operator %. The circular nature of the queue allows for efficient enqueue and dequeue operations without the need for shifting elements. The member functions isEmpty() and isFull() check if the queue is empty or full, respectively. The enqueue() function adds an element to the rear of the queue, the dequeue() function removes the front element from the queue, and the front() function returns the front element without removing it. The size() function returns the number of elements in the queue.

In the main function, we demonstrate how to use the Circular Queue by enqueueing and dequeueing elements and checking the front element and queue size.