Array Deletion at End in DSA Go - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to remove the last element from the slice.

DSA Go

arr = arr[:[1]]

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

A1

Blen(arr) - 1

C0

Dlen(arr)

Attempts:

3 left

💡 Hint

Common Mistakes

Using len(arr) which does not remove any element

Using 0 which empties the slice

Using 1 which keeps only the first element

To delete the last element, slice up to length minus one.

2fill in blank

medium

Complete the code to safely delete the last element only if the slice is not empty.

DSA Go

if len(arr) > 0 {
    arr = arr[:[1]]
}

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

Alen(arr) - 1

B0

Clen(arr)

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Slicing with len(arr) which does not remove element

Not checking if slice is empty before slicing

Check length first, then slice up to length minus one to remove last element.

3fill in blank

hard

Fix the error in the code to remove the last element from the slice.

DSA Go

arr = arr[:[1]]
// Error: runtime panic: slice bounds out of range

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

A0

Blen(arr) + 1

Clen(arr)

Dlen(arr) - 1

Attempts:

3 left

💡 Hint

Common Mistakes

Using len(arr) + 1 causing panic

Using len(arr) which does not remove element

Using len(arr) + 1 causes out of range error. Use len(arr) - 1 to remove last element.

4fill in blank

hard

Complete the code to remove the last element and print the updated slice.

DSA Go

arr = arr[:[1]]
fmt.Println(arr)

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

Alen(arr) - 1

B)

D(len(arr))

Attempts:

3 left

💡 Hint

Common Mistakes

Using len(arr) which does not remove element

Missing closing parenthesis in print

Slice up to len(arr) - 1 to remove last element, then print with closing parenthesis.

5fill in blank

hard

Fill both blanks to remove the last element, check if slice is empty, and print the result.

DSA Go

if len(arr) > 0 {
    arr = arr[:[1]]
}
if len(arr) == 0 {
    fmt.Println([2])
} else {
    fmt.Println(arr)
}

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

Alen(arr) - 1

B"Empty slice"

C)

Dlen(arr)

Attempts:

3 left

💡 Hint

Common Mistakes

Not checking slice length before slicing

Incorrect print syntax

Not handling empty slice case

Slice up to len(arr) - 1 to remove last element. Print "Empty slice" if empty, else print slice with closing parenthesis.

Practice

1. What happens when you delete an element from the end of an array in Go?

easy

A. The last element is removed and the array size decreases by one.

B. The first element is removed and the array size decreases by one.

C. The array size stays the same but the last element becomes zero.

D. The array is completely cleared and becomes empty.

Solution

1. Step 1: Understand array deletion at end

   Deleting at the end means removing the last element only, not the first or all.

2. Step 2: Effect on array size

   After removal, the array size decreases by one because one element is gone.

3. Final Answer:

   The last element is removed and the array size decreases by one. -> Option A

4. Quick Check:

   Deleting end element reduces size by one [OK]

Hint: Deleting at end removes last element and shrinks array [OK]

Common Mistakes:

• Thinking first element is removed
• Assuming array size stays same
• Believing array clears completely

2. Which of the following Go code snippets correctly deletes the last element from a slice named arr?

easy

A. arr = arr[len(arr):]

B. arr = arr[:len(arr)-1]

C. arr = arr[1:]

D. arr = arr[:len(arr)+1]

Solution

1. Step 1: Understand slice slicing syntax

   To remove last element, slice up to length minus one: arr[:len(arr)-1].

2. Step 2: Check other options

   arr[len(arr):] results in empty slice, arr[1:] removes first element, arr[:len(arr)+1] causes runtime error.

3. Final Answer:

   arr = arr[:len(arr)-1] -> Option B

4. Quick Check:

   Slice up to len-1 removes last element [OK]

Hint: Use arr[:len(arr)-1] to drop last element [OK]

Common Mistakes:

• Using arr[1:] removes first element
• Using arr[len(arr):] gives empty slice
• Using arr[:len(arr)+1] causes error

3. What is the output of this Go code?

arr := []int{10, 20, 30, 40}
arr = arr[:len(arr)-1]
fmt.Println(arr)

medium

A. [10 20 30 40]

B. []

C. [10 20 30]

D. [20 30 40]

Solution

1. Step 1: Initial array and slicing

   arr starts as [10 20 30 40]. Slicing arr[:len(arr)-1] means arr[:3].

2. Step 2: Result after slicing

   arr[:3] gives first three elements: [10 20 30].

3. Final Answer:

   [10 20 30] -> Option C

4. Quick Check:

   Slice up to len-1 excludes last element [OK]

Hint: Slicing arr[:len(arr)-1] drops last element [OK]

Common Mistakes:

• Expecting last element to remain
• Confusing arr[1:] with arr[:len(arr)-1]
• Thinking output is empty slice

4. Identify the error in this Go code that tries to delete the last element from arr:

arr := []int{1, 2, 3}
arr = arr[:len(arr)]
fmt.Println(arr)

medium

A. It deletes all elements making the array empty.

B. It causes a runtime panic due to invalid slice bounds.

C. It deletes the first element instead of the last.

D. It does not delete any element; array remains unchanged.

Solution

1. Step 1: Analyze slicing bounds

   arr[:len(arr)] means slice from start to full length, so no element is removed.

2. Step 2: Effect on array

   Since slice covers entire array, arr remains [1 2 3] unchanged.

3. Final Answer:

   It does not delete any element; array remains unchanged. -> Option D

4. Quick Check:

   Slicing arr[:len(arr)] keeps full array [OK]

Hint: arr[:len(arr)] keeps full array, no deletion [OK]

Common Mistakes:

• Assuming last element is deleted
• Expecting runtime error
• Thinking first element is removed

5. Given a slice arr := []int{5, 10, 15, 20, 25}, write the Go code to delete the last two elements and print the resulting slice.

hard

A. arr = arr[:len(arr)-2]
fmt.Println(arr)

B. arr = arr[2:]
fmt.Println(arr)

C. arr = arr[:len(arr)-1]
fmt.Println(arr)

D. arr = arr[1:len(arr)-1]
fmt.Println(arr)

Solution

1. Step 1: Understand deletion of last two elements

   To remove last two elements, slice up to length minus two: arr[:len(arr)-2].

2. Step 2: Apply slicing and print

   arr[:3] gives [5 10 15]. Printing arr shows these three elements.

3. Final Answer:

   arr = arr[:len(arr)-2] fmt.Println(arr) -> Option A

4. Quick Check:

   Slice up to len-2 removes last two elements [OK]

Hint: Use arr[:len(arr)-2] to remove last two elements [OK]

Common Mistakes:

• Using arr[2:] removes first two elements
• Removing only last element instead of two
• Incorrect slice bounds causing errors