How to use pointers to create a linked list queue C++ Draw the fallowing... e.g.

Question

How to use pointers to create a linked list queue C++

Draw the fallowing...

e.g. Second Front >Next:W know the second node delete Front; Front Second W Front moves down to the second node Q7% Draw the picture (snapshot) after each step. We cannot do the following: f node is gone and Front is now dangling delete Front Front Front->Next; segmentation fault Q8*: Draw the picture (snapshot) after each step. We cannot do the following: Front Front->Next:W front moves down delete Front; Il deleting the second node Q9*: Draw the picture (snapshot) after each step.

Explanation / Answer

Please find my implementation of Queue using Linked list.

Please repost others question in separate post.

#include <iostream>
#include <cstdlib>

using namespace std;
// A linked list (LL) node to store a queue entry
struct QNode
{
    int key;
    QNode *next;
};

// The queue, front stores the front node of LL and rear stores ths
// last node of LL
struct Queue
{
    QNode *front, *rear;
};

// A utility function to create a new linked list node.
QNode* newNode(int k)
{
     QNode *temp = new QNode;
    temp->key = k;
    temp->next = NULL;
    return temp;
}

// A utility function to create an empty queue
Queue *createQueue()
{
     Queue *q = new Queue;
    q->front = q->rear = NULL;
    return q;
}

// The function to add a key k to q
void enQueue( Queue *q, int k)
{
    // Create a new LL node
     QNode *temp = newNode(k);

    // If queue is empty, then new node is front and rear both
    if (q->rear == NULL)
    {
       q->front = q->rear = temp;
       return;
    }

    // Add the new node at the end of queue and change rear
    q->rear->next = temp;
    q->rear = temp;
}

// Function to remove a key from given queue q
QNode *deQueue( Queue *q)
{
    // If queue is empty, return NULL.
    if (q->front == NULL)
       return NULL;

    // Store previous front and move front one node ahead
     QNode *temp = q->front;
    q->front = q->front->next;

    // If front becomes NULL, then change rear also as NULL
    if (q->front == NULL)
       q->rear = NULL;
    return temp;
}

// Driver Program to test anove functions
int main()
{
     Queue *q = createQueue();
    enQueue(q, 10);
    enQueue(q, 20);
    deQueue(q);
    deQueue(q);
    enQueue(q, 30);
    enQueue(q, 40);
    enQueue(q, 50);
     QNode *n = deQueue(q);
    if (n != NULL)
      cout<<"Dequeued item is "<<n->key<<endl;
    return 0;
}

Related Questions

Navigate

• Browse (All)
• Browse H
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.