Q: What is a Linear Queue?
A:
- A linear queue is a basic queue data structure where elements are stored in a linear or sequential manner.
- It follows the First In, First Out (FIFO) principle.
Q: What is a Circular Queue?
A:
- A circular queue is an extension of a linear queue with the last element pointing to the first element, creating a circular structure.
- It overcomes the limitation of a linear queue by efficiently utilizing space.
Q: How is Memory Utilization Different in Linear and Circular Queues?
A:
- In a linear queue, if the queue is full and space is available at the beginning, it cannot be utilized.
- In a circular queue, space is efficiently utilized, and elements wrap around, allowing for better memory usage.
Q: How to Implement a Linear Queue?
A:
Linear Queue Example (in Python):
class LinearQueue:
def __init__(self, capacity):
self.capacity = capacity
self.queue = [None] * capacity
self.front = self.rear = -1
def is_empty(self):
return self.front == -1
def is_full(self):
return (self.rear + 1) % self.capacity == self.front
def enqueue(self, item):
if self.is_full():
print("Queue is full. Cannot enqueue.")
else:
if self.is_empty():
self.front = self.rear = 0
else:
self.rear = (self.rear + 1) % self.capacity
self.queue[self.rear] = item
def dequeue(self):
if self.is_empty():
print("Queue is empty. Cannot dequeue.")
return None
else:
item = self.queue[self.front]
if self.front == self.rear:
self.front = self.rear = -1
else:
self.front = (self.front + 1) % self.capacity
return item
```
Q: How to Implement a Circular Queue?
A:
Circular Queue Example (in Python):
class CircularQueue:
def __init__(self, capacity):
self.capacity = capacity
self.queue = [None] * capacity
self.front = self.rear = -1
def is_empty(self):
return self.front == -1
def is_full(self):
return (self.rear + 1) % self.capacity == self.front
def enqueue(self, item):
if self.is_full():
print("Queue is full. Cannot enqueue.")
else:
if self.is_empty():
self.front = self.rear = 0
else:
self.rear = (self.rear + 1) % self.capacity
self.queue[self.rear] = item
def dequeue(self):
if self.is_empty():
print("Queue is empty. Cannot dequeue.")
return None
else:
item = self.queue[self.front]
if self.front == self.rear:
self.front = self.rear = -1
else:
self.front = (self.front + 1) % self.capacity
return item
```
Q: When to Use Linear Queue vs Circular Queue?
A:
- Use a linear queue when you have a fixed size and don't need to reuse space at the beginning when elements are dequeued.
- Use a circular queue when efficient memory utilization is required, and you want to reuse space as elements are dequeued.
Q: How to Handle Overflow and Underflow in Circular Queue?
A:
- Overflow occurs when trying to enqueue into a full circular queue.
- Underflow occurs when trying to dequeue from an empty circular queue.
- Both situations can be handled by appropriate checks and error messages, as shown in the example codes.
Q: Can the Size of Linear and Circular Queues be Dynamically Altered?
A:
- The size of a linear queue is usually fixed once it is created.
- The size of a circular queue can be dynamically altered if a dynamic data structure like a linked list is used to implement it.
Important Interview Questions and Answers on Linear vs Circular Queue
Q: What is a Linear Queue?
A linear queue is a data structure in which elements are added at one end, called the rear, and removed from the other end, called the front. It follows the First In First Out (FIFO) principle.
Q: Explain the operations in a Linear Queue.
The main operations are:
- Enqueue: Adds an element to the rear of the queue.
- Dequeue: Removes an element from the front of the queue.
- Front: Returns the front element without removing it.
- Rear: Returns the rear element without removing it.
Q: Write a Python code for a Linear Queue.
Here is the code.
class LinearQueue:
def __init__(self):
self.queue = []
def enqueue(self, item):
self.queue.append(item)
def dequeue(self):
if not self.is_empty():
return self.queue.pop(0)
else:
return None
def front(self):
return self.queue[0] if not self.is_empty() else None
def rear(self):
return self.queue[-1] if not self.is_empty() else None
def is_empty(self):
return len(self.queue) == 0
def size(self):
return len(self.queue)
Q: What is a Circular Queue?
A circular queue is a variation of a linear queue in which the rear points to the front, forming a circle. This avoids wasting space and allows efficient utilization of memory.
Q: Explain the advantage of using a Circular Queue.
Circular Queue avoids the shifting of elements that occurs in a linear queue when the front element is dequeued, making it more efficient in terms of memory and operations.
Q: Write a Python code for a Circular Queue.
Here is the code.
class CircularQueue:
def __init__(self, capacity):
self.queue = [None] * capacity
self.front = self.rear = -1
self.capacity = capacity
def enqueue(self, item):
if (self.rear + 1) % self.capacity == self.front:
print("Queue is full. Cannot enqueue.")
elif self.is_empty():
self.front = self.rear = 0
self.queue[self.rear] = item
else:
self.rear = (self.rear + 1) % self.capacity
self.queue[self.rear] = item
def dequeue(self):
if self.is_empty():
print("Queue is empty. Cannot dequeue.")
return None
elif self.front == self.rear:
item = self.queue[self.front]
self.front = self.rear = -1
return item
else:
item = self.queue[self.front]
self.front = (self.front + 1) % self.capacity
return item
def front(self):
return self.queue[self.front] if not self.is_empty() else None
def rear(self):
return self.queue[self.rear] if not self.is_empty() else None
def is_empty(self):
return self.front == self.rear == -1
def is_full(self):
return (self.rear + 1) % self.capacity == self.front
