Dequeue Using Linked List in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new node with given data.

DSA C

struct Node* newNode(int data) {
    struct Node* temp = (struct Node*)malloc(sizeof(struct Node));
    temp->data = [1];
    temp->prev = NULL;
    temp->next = NULL;
    return temp;
}

Drag options to blanks, or click blank then click option'

Adata

BNULL

Ctemp

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning NULL or 0 instead of the input data.

Using the pointer variable instead of the data value.

The new node's data field should be set to the input parameter data.

2fill in blank

medium

Complete the code to insert a node at the front of the dequeue.

DSA C

void insertFront(struct Dequeue* dq, int data) {
    struct Node* temp = newNode(data);
    if (dq->front == NULL) {
        dq->front = dq->rear = temp;
    } else {
        temp->next = dq->front;
        dq->front->prev = [1];
        dq->front = temp;
    }
}

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Adq->rear

BNULL

Ctemp

Ddq->front

Attempts:

3 left

💡 Hint

Common Mistakes

Setting prev pointer to NULL or rear instead of the new node.

Not updating the prev pointer at all.

The previous pointer of the old front node should point to the new node temp.

3fill in blank

hard

Fix the error in the code to delete a node from the rear of the dequeue.

DSA C

void deleteRear(struct Dequeue* dq) {
    if (dq->rear == NULL) return;
    struct Node* temp = dq->rear;
    dq->rear = dq->rear->prev;
    if (dq->rear != NULL) {
        dq->rear->next = [1];
    } else {
        dq->front = NULL;
    }
    free(temp);
}

Drag options to blanks, or click blank then click option'

Adq->rear

Btemp

Cdq->front

DNULL

Attempts:

3 left

💡 Hint

Common Mistakes

Setting next pointer to temp or rear instead of NULL.

Not updating the next pointer after deletion.

After removing the rear node, the new rear's next pointer should be set to NULL to mark the end of the list.

4fill in blank

hard

Fill both blanks to insert a node at the rear of the dequeue correctly.

DSA C

void insertRear(struct Dequeue* dq, int data) {
    struct Node* temp = newNode(data);
    if (dq->rear == NULL) {
        dq->front = dq->rear = temp;
    } else {
        dq->rear->next = [1];
        temp->prev = [2];
        dq->rear = temp;
    }
}

Drag options to blanks, or click blank then click option'

Atemp

Bdq->front

Cdq->rear

DNULL

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up prev and next pointers.

Setting pointers to NULL incorrectly.

The current rear's next pointer should point to the new node temp, and the new node's prev pointer should point back to the current rear node.

5fill in blank

hard

Fill all three blanks to delete a node from the front of the dequeue correctly.

DSA C

void deleteFront(struct Dequeue* dq) {
    if (dq->front == NULL) return;
    struct Node* temp = dq->front;
    dq->front = dq->front->[1];
    if (dq->front != NULL) {
        dq->front->[2] = [3];
    } else {
        dq->rear = NULL;
    }
    free(temp);
}

Drag options to blanks, or click blank then click option'

Anext

Bprev

CNULL

Dfront

Attempts:

3 left

💡 Hint

Common Mistakes

Using prev instead of next to move front pointer.

Not setting prev pointer of new front to NULL.

Setting pointers to wrong nodes.

After deleting the front node, update dq->front to its next node, then set the new front's prev pointer to NULL to mark the start of the list.