Insertion and deletion operations on a Deque.

dequeOperations.c

#include<stdio.h>
#include<stdlib.h>
#define SIZE 15

int Deque[SIZE], front = -1, rear = -1;


void display()
{
	int i;
	if(front == -1)
	{
		printf("\nEmpty!");
		exit(1);
	}
	else if(front <= rear)
	{
		printf("\nState of the Deque is: \n");
		for(i = front; i <= rear; i++)
		{
			printf("%d\t", Deque[i]);
		}
	}
	else
	{
		printf("\nState of the Deque is: \n");

		for(i = front; i <= SIZE-1; i++)
		{
			printf("%d\t", Deque[i]);
		}

		for(i = 0; i <= rear; i++)
		{
			printf("%d\t", Deque[i]);
		}
	}

	printf("\n");
}

void insertAtRear(int el)
{
	if(rear + 1 == front || (front == 0) && (rear == SIZE-1))
	{
		printf("\nOverflow!\n");
		exit(1);
	}
	else if(rear == SIZE - 1)
	{
		rear = 0;
	}
	else
	{
		if(front == -1 && rear == -1)
		{
			front = 0;
		}
		rear+=1;
	}
	Deque[rear] = el;
	printf("\nFront = %d, Rear = %d", front, rear);
	display();
}

void deleteAtFront()
{
	int item = Deque[front];
	if(front == -1)
	{
		printf("\nUnderflow!\n");
		exit(1);
	}
	else
	{
		if(front == rear)
		{
			front = rear = -1;
		}
		else if(front == SIZE - 1)
		{
			front = 0;
		}
		else
		{
			front += 1;
		}
	}
	printf("\nThe item removed was %d\nFront = %d, Rear = %d", item, front, rear);
	display();
}

void insertAtFront(int el)
{
	if((front == 0 && rear == SIZE-1) || front == rear + 1)
	{
		printf("\nOverflow!\n");
		exit(1);
	}
	else if(front == -1 && rear == -1)
	{
		rear = 0;
		front = 0;
	}
	else if(front == 0)
	{
		front = SIZE - 1;
	}
	else
	{
		front--;
	}
	Deque[front] = el;
	printf("\nFront = %d, Rear = %d", front, rear);
	display();
}

void deleteAtRear()
{
	int item = Deque[rear];
	if(front == -1)
	{
		printf("\nUnderflow!\n");
		exit(1);
	}
	else if(front == rear)
	{
		front = rear = -1;
	}
	else if(rear == 0)
	{
		rear = SIZE - 1;
	}
	else
	{
		rear--;
	}
	printf("\nThe item removed was %d, Front = %d, Rear = %d\n", item, front, rear);
	display();
}

void inputRestricted()
{
    char choice, cont;
    int el;
	do{
		printf("\n1.Insert at rear\n2.Delete at front\n3.Delete at rear\n4.Display\nEnter your choice: ");
		choice = getche();
		switch(choice)
		{
			case '1':
				printf("\nEnter the element to be inserted: ");
				scanf("%d", &el);
				insertAtRear(el);
				break;
			case '2':
				deleteAtFront();
				break;
			case '3':
				deleteAtRear();
				break;
			case '4':
				display();
				break;
			default:
				printf("\nInvalid option!");
				break;
		}
		//printf("\nWant to continue? ");
		//choice = getche();
	}while(1);
}

void outputRestricted()
{
    char choice, cont;
    int el;
	do{
		printf("\n1.Delete at front\n2.Insert at front\n3.Insert at rear\n4.Display\nEnter your choice: ");
		choice = getche();
		switch(choice)
		{
			case '1':
				deleteAtFront();
				break;
			case '2':
				printf("\nEnter the element to be inserted: ");
				scanf("%d", &el);
				insertAtFront(el);
				break;
			case '3':
			    printf("\nEnter the element to be inserted: ");
				scanf("%d", &el);
				insertAtRear(el);
				break;
			case '4':
				display();
				break;
			default:
				printf("\nInvalid option!");
				break;
		}
		printf("\nWant to continue? ");
		cont = getche();
	}while(cont == 'y' || cont == 'Y');
}

void main()
{
	char choice;
    printf("\n1.Input Restricted Queue\n2.output Restricted Queue? ");
    choice = getche();
    switch(choice)
    {
        case '1':
            inputRestricted();
            break;
        case '2':
            outputRestricted();
            break;
        default:
            printf("\nInvalid option!");
    }
}