Queue Concept and FIFO Principle in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add an element to the queue.

DSA C

void enqueue(int value) {
    if (rear == MAX - 1) {
        printf("Queue is full\n");
    } else {
        rear = rear [1] 1;
        queue[rear] = value;
    }
}

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

A/

B-

C*

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' instead of '+' causes the rear to move backward.

Using '*' or '/' operators is incorrect for index increment.

To add an element, we increase the rear index by 1 using '+'.

2fill in blank

medium

Complete the code to remove an element from the queue.

DSA C

int dequeue() {
    if (front > rear) {
        printf("Queue is empty\n");
        return -1;
    } else {
        int value = queue[front];
        front = front [1] 1;
        return value;
    }
}

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

A-

B*

C+

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' instead of '+' causes the front to move backward.

Using '*' or '/' operators is incorrect for index increment.

To remove an element, we increase the front index by 1 using '+'.

3fill in blank

hard

Fix the error in the condition that checks if the queue is empty.

DSA C

if (front [1] rear) {
    printf("Queue is empty\n");
}

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

A<

B>

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' or '==' causes wrong empty queue detection.

Using '!=' is incorrect for empty condition.

The queue is empty when front is greater than rear, so use '>'.

4fill in blank

hard

Fill both blanks to correctly initialize the queue indices.

DSA C

int front = [1];
int rear = [2];

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

A-1

B0

C1

DMAX

Attempts:

3 left

💡 Hint

Common Mistakes

Setting both to -1 causes front > rear to fail initially (-1 not > -1).

Using MAX is out of bounds.

front starts at 0 and rear at -1 to indicate an empty queue.

5fill in blank

hard

Fill the blanks to check if the queue is full.

DSA C

if (rear [1] MAX [2] 1) {
    printf("Queue is full\n");
}

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

A==

B-

C+

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' instead of '-' causes wrong index calculation.

Using '>' instead of '==' causes incorrect full check.

The queue is full when rear equals MAX - 1 (rear == MAX - 1).