Using additional non-array variables, order all elements on a queue using also a

Question

Using additional non-array variables, order all elements on a queue using also

a) two additional queues

b) one additional queue

Explanation / Answer

* C Program to Implement Queue Data Structure using Linked List */ #include #include struct node { int info; struct node *ptr; }*front,*rear,*temp,*front1; int frontelement(); void enq(int data); void deq(); void empty(); void display(); void create(); void queuesize(); int count = 0; void main() { int no, ch, e; printf(" 1 - Enque"); printf(" 2 - Deque"); printf(" 3 - Front element"); printf(" 4 - Empty"); printf(" 5 - Exit"); printf(" 6 - Display"); printf(" 7 - Queue size"); create(); while (1) { printf(" Enter choice : "); scanf("%d", &ch); switch (ch) { case 1: printf("Enter data : "); scanf("%d", &no); enq(no); break; case 2: deq(); break; case 3: e = frontelement(); if (e != 0) printf("Front element : %d", e); else printf(" No front element in Queue as queue is empty"); break; case 4: empty(); break; case 5: exit(0); case 6: display(); break; case 7: queuesize(); break; default: printf("Wrong choice, Please enter correct choice "); break; } } } /* Create an empty queue */ void create() { front = rear = NULL; } /* Returns queue size */ void queuesize() { printf(" Queue size : %d", count); } /* Enqueing the queue */ void enq(int data) { if (rear == NULL) { rear = (struct node *)malloc(1*sizeof(struct node)); rear->ptr = NULL; rear->info = data; front = rear; } else { temp=(struct node *)malloc(1*sizeof(struct node)); rear->ptr = temp; temp->info = data; temp->ptr = NULL; rear = temp; } count++; } /* Displaying the queue elements */ void display() { front1 = front; if ((front1 == NULL) && (rear == NULL)) { printf("Queue is empty"); return; } while (front1 != rear) { printf("%d ", front1->info); front1 = front1->ptr; } if (front1 == rear) printf("%d", front1->info); } /* Dequeing the queue */ void deq() { front1 = front; if (front1 == NULL) { printf(" Error: Trying to display elements from empty queue"); return; } else if (front1->ptr != NULL) { front1 = front1->ptr; printf(" Dequed value : %d", front->info); free(front); front = front1; } else { printf(" Dequed value : %d", front->info); free(front); front = NULL; rear = NULL; } count--; } /* Returns the front element of queue */ int frontelement() { if ((front != NULL) && (rear != NULL)) return(front->info); else return 0; } /* Display if queue is empty or not */ void empty() { if ((front == NULL) && (rear == NULL)) printf(" Queue empty"); else printf("Queue not empty"); }

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