deque.cpp11.cpp

#include <iostream>
using namespace std;
#define SIZE 5
int deque[SIZE];
int front = -1, rear = -1;
void insertFront(int x) {
    if ((front == 0 && rear == SIZE - 1) || (front == rear + 1)) {
        cout << "Deque Overflow\n";
        return;
    }
    if (front == -1) {
        front = rear = 0;
    }
    else if (front == 0) {
        front = SIZE - 1;
    }
    else {
        front--;
    }
    deque[front] = x;
    cout << x << " inserted at front\n";
}
void insertRear(int x) {
    if ((front == 0 && rear == SIZE - 1) || (front == rear + 1)) {
        cout << "Deque Overflow\n";
        return;
    }
    if (rear == -1) {
        front = rear = 0;
    }
    else if (rear == SIZE - 1) {
        rear = 0;
    }
    else {
        rear++;
    }
    deque[rear] = x;
    cout << x << " inserted at rear\n";
}
void deleteFront() {
    if (front == -1) {
        cout << "Deque Underflow\n";
        return;
    }
    cout << deque[front] << " deleted from front\n";

    if (front == rear) {
        front = rear = -1;
    }
    else if (front == SIZE - 1) {
        front = 0;
    }
    else {
        front++;
    }
}
void deleteRear() {
    if (rear == -1) {
        cout << "Deque Underflow\n";
        return;
    }
    cout << deque[rear] << " deleted from rear\n";
    if (front == rear) {
        front = rear = -1;
    }
    else if (rear == 0) {
        rear = SIZE - 1;
    }
    else {
        rear--;
    }
}
void display() {
    if (front == -1) {
        cout << "Deque is empty\n";
        return;
    }
    cout << "Deque elements: ";
    int i = front;
    while (true) {
        cout << deque[i] << " ";
        if (i == rear)
            break;
        i = (i + 1) % SIZE;
    }
    cout << endl;
}
int main() {
    insertRear(10);
    insertRear(20);
    insertFront(5);
    display();

    deleteFront();
    deleteRear();
    display();
    return 0;
}