Linked list vs array comparison in Data Structures Theory - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the sentence to describe arrays: Arrays store elements in {{BLANK_1}} locations.

Data Structures Theory

Arrays store elements in [1] locations.

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

Arandom

Bcontiguous

Clinked

Dscattered

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'random' or 'scattered' because elements can be accessed randomly.

Arrays store elements in contiguous memory locations, meaning elements are placed one after another in memory.

2fill in blank

medium

Complete the sentence to describe linked lists: Each element in a linked list contains data and a {{BLANK_1}} to the next element.

Data Structures Theory

Each element in a linked list contains data and a [1] to the next element.

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

Apointer

Bvalue

Cindex

Dsize

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'index' because linked lists do not use indexes like arrays.

In a linked list, each element has a pointer (or reference) to the next element, allowing dynamic linking.

3fill in blank

hard

Fix the error in this statement: Arrays have {{BLANK_1}} insertion and deletion at the beginning compared to linked lists.

Data Structures Theory

Arrays have [1] insertion and deletion at the beginning compared to linked lists.

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

Aslower

Bfaster

Cequal

Dno

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'faster' because arrays allow quick access, but insertion/deletion is different.

Arrays have slower insertion and deletion at the beginning because elements need to be shifted, unlike linked lists which can adjust pointers quickly.

4fill in blank

hard

Fill both blanks to complete the comparison: Arrays have {{BLANK_1}} access time but {{BLANK_2}} memory usage than linked lists.

Data Structures Theory

Arrays have [1] access time but [2] memory usage than linked lists.

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

Afaster

Bhigher

Cslower

Dlower

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up access speed or memory usage between arrays and linked lists.

Arrays provide faster access time because elements are contiguous, but they use lower memory since they don't store pointers like linked lists.

5fill in blank

hard

Fill all three blanks to complete the statement: Linked lists {{BLANK_1}} dynamic size, {{BLANK_2}} easy insertion, and {{BLANK_3}} slower random access compared to arrays.

Data Structures Theory

Linked lists [1] dynamic size, [2] easy insertion, and [3] slower random access compared to arrays.

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

Asupport

Ballow

Chave

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same verb for all blanks without considering meaning.

Linked lists support dynamic size, allow easy insertion, and have slower random access compared to arrays.

Practice

1. Which data structure stores elements in continuous memory locations?

easy

A. Linked list

B. Graph

C. Tree

D. Array

Solution

1. Step 1: Understand array memory layout

   Arrays store elements in continuous memory blocks, allowing direct access by index.

2. Step 2: Compare with linked list memory layout

   Linked lists store elements in nodes scattered in memory, connected by pointers.

3. Final Answer:

   Array -> Option D

4. Quick Check:

   Continuous memory = Array [OK]

Hint: Continuous memory means array, not linked list [OK]

Common Mistakes:

• Confusing linked list nodes as continuous
• Thinking trees or graphs store data continuously
• Assuming arrays use pointers between elements

2. Which of the following is the correct way to access the 3rd element in an array named arr?

easy

A. arr[3]

B. arr(3)

C. arr[2]

D. arr->3

Solution

1. Step 1: Recall zero-based indexing in arrays

   Arrays start counting from 0, so the first element is arr[0], second arr[1], third arr[2].

2. Step 2: Identify correct syntax

   Using square brackets with index 2 accesses the third element correctly.

3. Final Answer:

   arr[2] -> Option C

4. Quick Check:

   Third element index = 2 [OK]

Hint: Array indexing starts at zero, so third element is index 2 [OK]

Common Mistakes:

• Using parentheses instead of brackets
• Using index 3 for third element
• Using pointer syntax incorrectly

3. Consider this code snippet using a linked list:

node1 = Node(10)
node2 = Node(20)
node1.next = node2
print(node1.next.data)

What will be the output?

medium

A. 20

B. node2

C. 10

D. Error

Solution

1. Step 1: Understand node linking

   node1.next points to node2, which holds data 20.

2. Step 2: Access data through next pointer

   node1.next.data accesses node2's data, which is 20.

3. Final Answer:

   20 -> Option A

4. Quick Check:

   node1.next.data = 20 [OK]

Hint: Follow the next pointer to get linked node's data [OK]

Common Mistakes:

• Printing node1.data instead of node1.next.data
• Confusing node reference with data value
• Expecting error due to missing initialization

4. What is wrong with this code snippet for inserting a new node at the start of a linked list?

new_node = Node(5)
new_node.next = head
head = new_node.next

medium

A. head should be assigned to new_node, not new_node.next

B. new_node.next should be null before assignment

C. Node creation syntax is incorrect

D. No error, code is correct

Solution

1. Step 1: Analyze pointer assignments

   new_node.next is set to head, which is correct to link new node to list.

2. Step 2: Check head update

   head should point to new_node to update list start, but code assigns head = new_node.next, losing new_node.

3. Final Answer:

   head should be assigned to new_node, not new_node.next -> Option A

4. Quick Check:

   Head must point to new node [OK]

Hint: Head must point to new node after insertion [OK]

Common Mistakes:

• Assigning head to new_node.next instead of new_node
• Not linking new_node.next to old head
• Confusing node creation with pointer assignment

5. You need to frequently add and remove elements from the middle of a collection. Which data structure is better and why?

hard

A. Array, because it allows fast random access

B. Linked list, because it allows easy insertion and deletion without shifting elements

C. Array, because it uses less memory

D. Linked list, because it stores elements in continuous memory

Solution

1. Step 1: Consider insertion and deletion costs

   Arrays require shifting elements when inserting or deleting in the middle, which is slow.

2. Step 2: Understand linked list flexibility

   Linked lists use pointers to connect nodes, so insertion and deletion in the middle is fast without shifting.

3. Final Answer:

   Linked list, because it allows easy insertion and deletion without shifting elements -> Option B

4. Quick Check:

   Frequent middle changes = Linked list [OK]

Hint: Use linked list for easy middle insert/delete [OK]

Common Mistakes:

• Choosing array for middle insert/delete ignoring shift cost
• Thinking linked list stores data continuously
• Assuming arrays always use less memory