Deque (double-ended queue) in Data Structures Theory - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the sentence to describe a deque.

Data Structures Theory

A deque allows insertion and removal of elements from both the [1] and the [2].

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Aback

Bmiddle

Cfront

Drandom

Attempts:

3 left

💡 Hint

Common Mistakes

Thinking elements can be added or removed from the middle.

Confusing deque with a stack or queue that only works on one end.

A deque (double-ended queue) supports adding and removing elements from both the front and the back ends.

2fill in blank

medium

Complete the sentence to explain deque operations.

Data Structures Theory

The operation to add an element at the back of a deque is called [1].

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Apush_back

Bdequeue

Cenqueue

Dpop_front

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'pop_front' which means removing from front.

Confusing enqueue and dequeue which are queue operations.

In a deque, adding an element at the back is called push_back.

3fill in blank

hard

Fix the error in the statement about deque removal.

Data Structures Theory

Removing an element from the front of a deque is done using [1].

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Apush_back

Bpush_front

Cpop_front

Dpop_back

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'push_front' which adds instead of removes.

Confusing 'pop_back' which removes from the back.

To remove an element from the front of a deque, the correct operation is pop_front.

4fill in blank

hard

Fill both blanks to describe deque usage.

Data Structures Theory

A deque can be used as a [1] or a [2] because it supports insertion and removal from both ends.

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Astack

Bqueue

Clist

Dtree

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'list' or 'tree' which are different data structures.

Not realizing deque can behave like both stack and queue.

A deque can act like a stack (LIFO) or a queue (FIFO) because it allows adding and removing elements from both ends.

5fill in blank

hard

Fill all three blanks to complete the Python deque example.

Data Structures Theory

from collections import [1]
d = [1]()
d.[2](5)  # add to back
d.pop[3]()  # remove from front

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

Adeque

Bappend

Cleft

Dlist

Attempts:

3 left

💡 Hint

Common Mistakes

Using list instead of deque, which is inefficient for front operations.

Using appendleft for back or pop for front.

Forgetting the specific method names in Python's deque.

In Python, deque from collections is used. append(5) adds to the back, and popleft() removes from the front.