Array Insertion at End in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to insert an element at the end of the array.

DSA Python

arr = [1, 2, 3]
arr.[1](4)
print(arr)

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

Aappend

Binsert

Cextend

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using insert without index causes error.

Using pop removes elements instead of adding.

The append method adds an element at the end of the list.

2fill in blank

medium

Complete the code to add multiple elements at the end of the array.

DSA Python

arr = [1, 2, 3]
arr.[1]([4, 5])
print(arr)

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

Aappend

Binsert

Cextend

Dremove

Attempts:

3 left

💡 Hint

Common Mistakes

Using append adds the list as a single element.

Using remove deletes elements instead of adding.

The extend method adds all elements from another list to the end.

3fill in blank

hard

Fix the error in the code to insert 10 at the end of the array.

DSA Python

arr = [5, 6, 7]
arr.[1](10, 3)
print(arr)

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

Apop

Binsert

Cextend

Dappend

Attempts:

3 left

💡 Hint

Common Mistakes

Using insert with wrong arguments causes error.

Using pop removes elements instead of adding.

append takes only one argument and adds it at the end. insert needs index and value, but here we want to add at the end simply.

4fill in blank

hard

Fill both blanks to insert 20 at the end of the array using insert method.

DSA Python

arr = [10, 15, 18]
arr.[1]([2], 20)
print(arr)

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

Ainsert

Bappend

Clen(arr)

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using index 0 inserts at the start, not the end.

Using append with two arguments causes error.

Using insert with index equal to the length of the array adds the element at the end.

5fill in blank

hard

Fill all three blanks to create a new array by adding 30 at the end using concatenation.

DSA Python

arr = [25, 27]
new_arr = arr [1] [[2]] [3]
print(new_arr)

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

A+

B30

C*

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using * repeats the list instead of adding an element.

Using - between lists causes error.

Using + concatenates lists. We add a list with one element 30. The - at the end is just to complete the code line (no operation here, but needed to fill blank).

Practice

1. What does inserting an element at the end of an array mean?

easy

A. Replacing the first element with the new element

B. Adding the new element after the last existing element

C. Removing the last element and adding the new one at the start

D. Inserting the new element in the middle of the array

Solution

1. Step 1: Understand array structure

   An array stores elements in order, from first to last.

2. Step 2: Define insertion at end

   Inserting at the end means placing the new element after the last element, extending the array.

3. Final Answer:

   Adding the new element after the last existing element -> Option B

4. Quick Check:

   Insert at end = add after last element [OK]

Hint: End insertion means add after last element [OK]

Common Mistakes:

• Confusing insertion at end with replacing elements
• Thinking insertion means removing elements
• Mixing up start and end positions

2. Which of the following Python statements correctly inserts the value 10 at the end of list arr?

easy

A. arr.append(10)

B. arr.insert(0, 10)

C. arr.add(10)

D. arr[10] = 10

Solution

1. Step 1: Recall Python list methods

   To add an element at the end, use append() method.

2. Step 2: Check each option

   arr.append(10) uses append(10), which adds 10 at the end. Others either insert at start, use invalid method, or wrong syntax.

3. Final Answer:

   arr.append(10) -> Option A

4. Quick Check:

   append() adds at end [OK]

Hint: Use append() to add at end of list [OK]

Common Mistakes:

• Using insert(0, value) which adds at start
• Trying to assign value to arr[10] without index existing
• Using non-existent method add()

3. What will be the output of the following code?

arr = [1, 2, 3]
arr.append(4)
print(arr)

medium

A. [1, 2, 3, 4]

B. Error

C. [1, 2, 3]

D. [4, 1, 2, 3]

Solution

1. Step 1: Understand initial array

   Array starts as [1, 2, 3].

2. Step 2: Apply append(4)

   Append adds 4 at the end, so array becomes [1, 2, 3, 4].

3. Final Answer:

   [1, 2, 3, 4] -> Option A

4. Quick Check:

   append(4) adds 4 at end [OK]

Hint: append() adds element at array's end [OK]

Common Mistakes:

• Thinking append adds at start
• Expecting original array unchanged
• Confusing append with insert

4. Find the error in the following code that tries to insert 5 at the end of the list nums:

nums = [1, 2, 3]
nums.insert(5)

medium

A. insert() cannot be used to add elements

B. nums is not a list

C. append() should be used instead of insert()

D. insert() requires two arguments: index and value

Solution

1. Step 1: Check insert() method signature

   insert() needs two arguments: position index and value to insert.

2. Step 2: Analyze given code

   Code calls insert(5) with only one argument, causing error.

3. Final Answer:

   insert() requires two arguments: index and value -> Option D

4. Quick Check:

   insert() needs index and value [OK]

Hint: insert() needs index and value arguments [OK]

Common Mistakes:

• Calling insert() with one argument
• Confusing insert() and append() usage
• Assuming insert() adds at end by default

5. You have an array arr = [2, 4, 6]. You want to add multiple elements [8, 10, 12] at the end efficiently. Which code snippet correctly does this?

hard

A. arr.append(8, 10, 12)

B. arr.append([8, 10, 12])

C. arr.extend([8, 10, 12])

D. arr.insert(len(arr), [8, 10, 12])

Solution

1. Step 1: Understand difference between append and extend

   append adds one element; extend adds all elements from iterable individually.

2. Step 2: Analyze options

   A: arr.append(8,10,12) passes multiple arguments to append(), causing TypeError. B: arr.append([8,10,12]) adds list as one element. arr.extend([8,10,12]) adds all elements individually at end. arr.insert(len(arr),[8,10,12]) inserts list as one element at end.

3. Final Answer:

   arr.extend([8, 10, 12]) -> Option C

4. Quick Check:

   extend() adds multiple elements at end [OK]

Hint: Use extend() to add multiple elements at once [OK]

Common Mistakes:

• Passing multiple arguments to append()
• Using append() to add list as single element
• Using insert() with list adds nested list