Array Insertion at End in DSA Rust - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add an element to the end of the vector.

DSA Rust

let mut numbers = vec![1, 2, 3];
numbers.[1](4);

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

Apush

Bpop

Cinsert

Dremove

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop instead of push removes an element instead of adding.

Using insert requires an index, not just a value.

The push method adds an element to the end of the vector.

2fill in blank

medium

Complete the code to print the last element after insertion.

DSA Rust

let mut nums = vec![10, 20, 30];
nums.push(40);
println!("{}", nums.[1]().unwrap());

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

Afirst

Bpop

Clast

Dremove

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop removes the element instead of just accessing it.

Using first accesses the first element, not the last.

The last method returns a reference to the last element in the vector.

3fill in blank

hard

Fix the error in the code to insert 50 at the end of the vector.

DSA Rust

let mut vals = vec![5, 15, 25];
vals.[1](50);

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

Apush

Binsert

Cremove

Dappend

Attempts:

3 left

💡 Hint

Common Mistakes

Using insert with arguments in wrong order causes error.

Using append incorrectly to add a single element.

push takes only one argument and adds the element at the end. insert requires index first, then value.

4fill in blank

hard

Fill both blanks to create a vector and add 100 at the end.

DSA Rust

let mut data = [1]![10, 20, 30];
data.[2](100);

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

Avec

Bpush

Cinsert

Darray

Attempts:

3 left

💡 Hint

Common Mistakes

Using array instead of vec! macro causes type errors.

Using insert instead of push requires an index.

vec! macro creates a vector; push adds an element at the end.

5fill in blank

hard

Fill all three blanks to create a vector, add 5, and print the last element.

DSA Rust

let mut numbers = [1]![1, 2, 3];
numbers.[2](5);
println!("{}", numbers.[3]().unwrap());

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

Avec

Bpush

Clast

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop removes the last element instead of accessing it.

Forgetting to unwrap the Option returned by last.

vec! creates vector, push adds element, last returns reference to last element.

Practice

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

easy

A. Sorting the array in ascending order

B. Removing the first item from the array

C. Replacing the first item in the array

D. Adding a new item after the last existing item in the array

Solution

1. Step 1: Understand array structure

   An array is a list of items stored in order, starting from the first to the last.

2. Step 2: Define insertion at the end

   Inserting at the end means placing a new item right after the last item, extending the array by one.

3. Final Answer:

   Adding a new item after the last existing item in the array -> Option D

4. Quick Check:

   Insert at end = Add after last [OK]

Hint: Think: new item goes after the last one [OK]

Common Mistakes:

• Confusing insertion at end with removal
• Thinking insertion replaces an item
• Mixing insertion with sorting

2. Which Rust code snippet correctly inserts the value 10 at the end of a mutable vector named vec?

easy

A. vec.push(10);

B. vec.insert(0, 10);

C. vec[vec.len()] = 10;

D. vec.append(10);

Solution

1. Step 1: Identify correct method to add at end

   In Rust, push adds an element to the end of a vector.

2. Step 2: Check other options

   insert(0, 10) adds at start, vec[vec.len()] = 10 causes error (index out of bounds), append(10) is invalid syntax.

3. Final Answer:

   vec.push(10); -> Option A

4. Quick Check:

   Use push() to add at end [OK]

Hint: Use push() to add at the end of a vector [OK]

Common Mistakes:

• Using insert with wrong index
• Trying to assign to vec[vec.len()] directly
• Using append with a single value

3. What will be the output of this Rust code?

let mut numbers = vec![1, 2, 3];
numbers.push(4);
println!("{:?}", numbers);

medium

A. [1, 2, 3]

B. [4, 1, 2, 3]

C. [1, 2, 3, 4]

D. Compilation error

Solution

1. Step 1: Understand initial vector

   The vector numbers starts as [1, 2, 3].

2. Step 2: Apply push operation

   numbers.push(4) adds 4 at the end, making it [1, 2, 3, 4].

3. Final Answer:

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

4. Quick Check:

   push(4) adds 4 at end [OK]

Hint: push() adds element at the end [OK]

Common Mistakes:

• Thinking push adds at start
• Expecting original vector unchanged
• Confusing output format

4. Identify the error in this Rust code that tries to insert 5 at the end of a vector:

let numbers = vec![1, 2, 3];
numbers.push(5);

medium

A. Cannot push because vector is immutable

B. push method does not exist for vectors

C. Syntax error in push call

D. No error, code runs fine

Solution

1. Step 1: Check vector mutability

   The vector numbers is declared without mut, so it is immutable.

2. Step 2: Understand push requirements

   push requires the vector to be mutable to add elements.

3. Final Answer:

   Cannot push because vector is immutable -> Option A

4. Quick Check:

   push needs mutable vector [OK]

Hint: Declare vector as mutable to push [OK]

Common Mistakes:

• Forgetting to add mut keyword
• Assuming push works on immutable vectors
• Misreading error as syntax problem

5. Given a vector vec with elements [2, 4, 6], write Rust code to insert the number 8 at the end and then remove the first element. What will be the final vector?

hard

A. [2, 4, 6, 8]

B. [4, 6, 8]

C. [8, 2, 4, 6]

D. [2, 4, 8]

Solution

1. Step 1: Insert 8 at the end

   Using vec.push(8), vector becomes [2, 4, 6, 8].

2. Step 2: Remove the first element

   Using vec.remove(0), removes 2, vector becomes [4, 6, 8].

3. Final Answer:

   [4, 6, 8] -> Option B

4. Quick Check:

   push then remove first = [4,6,8] [OK]

Hint: Push adds end, remove(0) deletes first [OK]

Common Mistakes:

• Removing last instead of first element
• Not updating vector after push
• Confusing remove index