Deque

Program of input and output restricted dequeue using array
# include<stdio.h>
# define MAX 5
int deque_arr[MAX];
int left = -1;
int right = -1;
main()
{
int choice;
printf("1.Input restricted dequeue\n");
printf("2.Output restricted dequeue\n");
printf("Enter your choice : ");
scanf("%d",&choice);
switch(choice) {
case 1 :
input_que();
break;
case 2:
output_que();
break;
default:
printf("Wrong choice\n");
}/*End of switch*/
}/*End of main()
*/
input_que()
{
int choice;
while(1) {
printf("1.Insert at right\n");
printf("2.Delete from left\n");
printf("3.Delete from right\n");
printf("4.Display\n");
printf("5.Quit\n");
printf("Enter your choice : ");
scanf("%d",&choice);
switch(choice)
{
case 1:
insert_right();
break;
case 2:
delete_left();
break;
case 3:
delete_right();
break;
case 4:
display_queue();
break;
case 5:
exit();
default:
printf("Wrong choice\n");
}/*End of switch*/
}/*End of while*/
}/*End of input_que() */
output_que()
{
int choice;
while(1) {
printf("1.Insert at right\n");
printf("2.Insert at left\n");
printf("3.Delete from left\n");
printf("4.Display\n");
printf("5.Quit\n");
printf("Enter your choice : ");
scanf("%d",&choice);
switch(choice)
{
case 1:
insert_right();
break;
case 2:
insert_left();
break;
case 3:
delete_left();
break;
case 4:
display_queue();
break;
case 5:
exit();
default: printf("Wrong choice\n");
}/*End of switch*/
}/*End of while*/
}/*End of output_que() */
insert_right()
{
int added_item;
if((left == 0 && right == MAX-1) || (left == right+1)) {
printf("Queue Overflow\n");
return;
}
if (left == -1)  /* if queue is initially empty */
{
left = 0;
right = 0;
}
else
if(right == MAX-1)  /*right is at last position of queue */
right = 0;
else
right = right+1;
printf("Input the element for adding in queue : ");
scanf("%d", &added_item);
deque_arr[right] = added_item ;
}/*End of insert_right()*/
insert_left()
{
int added_item;
if((left == 0 && right == MAX-1) || (left == right+1))
{
printf("Queue Overflow \n");
return;
}
if (left == -1)/*If queue is initially empty*/
{
left = 0;
right = 0;
}
else
if(left== 0) left=MAX-1;
else
left=left-1;
printf("Input the element for adding in queue : ");
scanf("%d", &added_item);
deque_arr[left] = added_item ;
}/*End of insert_left()*/
delete_left()
{
if (left == -1)
{
printf("Queue Underflow\n");
return ;
}
printf("Element deleted from queue is : %d\n",deque_arr[left]);
if(left == right) /*Queue has only one element */
{
left = -1;
right=-1;
}
else
if(left == MAX-1)
left = 0;
else
left = left+1;
}/*End of delete_left()*/
delete_right()
{
if (left == -1)
{
printf("Queue Underflow\n");
return ;
} printf("Element deleted from queue is : %d\n",deque_arr[right]);
if(left == right) /*queue has only one element*/
{
left = -1;
right=-1;
}
else
if(right == 0)
right=MAX-1;
else
right=right-1;
}/*End of delete_right() */
display_queue()
{
int front_pos = left,rear_pos = right;
if(left == -1) {
printf("Queue is empty\n");
return;
}
printf("Queue elements :\n");
if( front_pos <= rear_pos ) {
while(front_pos <= rear_pos)
{
printf("%d ",deque_arr[front_pos]);
front_pos++;
}
}
else
{
while(front_pos <= MAX-1)
{
printf("%d ",deque_arr[front_pos]);
front_pos++;
}
front_pos = 0;
while(front_pos <= rear_pos)
{
printf("%d ",deque_arr[front_pos]);
front_pos++;
}
}/*End of else
*/
printf("\n");
}/*End of display_queue() */