Array Deletion at End in DSA C - Practice Problems & Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output after deleting the last element from the array?

Consider the following C code that deletes the last element from an array by reducing its size. What will be printed?

DSA C

int arr[5] = {10, 20, 30, 40, 50};
int size = 5;

// Delete last element
if (size > 0) {
    size--;
}

for (int i = 0; i < size; i++) {
    printf("%d ", arr[i]);
}
printf("\n");

A 10 20 30 40

B 10 20 30 40 50

C 20 30 40 50

D 10 20 30 50

💡 Hint

Deleting the last element means reducing the size by one and printing only up to the new size.

The array elements remain the same in memory, but the size variable is reduced by one. So the loop prints elements from index 0 to size-1, which excludes the last element 50.

❓ Predict Output

intermediate

What happens if we delete from an empty array?

Given the code below, what will be the output?

DSA C

int arr[3] = {1, 2, 3};
int size = 0;

if (size > 0) {
    size--;
}

printf("Size: %d\n", size);

A Runtime error

B Size: 0

C Size: 1

D Size: -1

💡 Hint

Check the condition before decreasing size.

Since size is 0, the if condition fails and size remains 0. So output is 'Size: 0'.

🔧 Debug

advanced

Why does this code print an extra element after deletion?

The code below tries to delete the last element from the array but prints one extra element. Identify the bug.

DSA C

int arr[4] = {5, 10, 15, 20};
int size = 4;

size = size - 1;

for (int i = 0; i < size; i++) {
    printf("%d ", arr[i]);
}
printf("\n");

A The array elements should be shifted left after deletion

B The size should not be decremented before the loop

C The loop condition should be i < size, not i <= size

D The array size should be reset to zero

💡 Hint

Check the loop boundary condition carefully.

Using i <= size causes the loop to run one extra time, printing arr[size], which is beyond the new last element.

❓ Predict Output

advanced

What is the output after multiple deletions at the end?

Given the code below, what will be printed?

DSA C

int arr[6] = {2, 4, 6, 8, 10, 12};
int size = 6;

// Delete last element twice
for (int i = 0; i < 2; i++) {
    if (size > 0) {
        size--;
    }
}

for (int i = 0; i < size; i++) {
    printf("%d ", arr[i]);
}
printf("\n");

A 2 4 6 8 10 12

B 2 4 6 8 10

C 4 6 8 10

D 2 4 6 8

💡 Hint

Each deletion reduces size by one, so two deletions reduce size from 6 to 4.

After two deletions, size is 4, so elements at indices 0 to 3 are printed: 2 4 6 8

🧠 Conceptual

expert

What is the time complexity of deleting the last element in a dynamic array?

Consider a dynamic array (like a vector in C++ or ArrayList in Java). What is the time complexity of deleting the last element?

A O(1) - Constant time

B O(n) - Linear time

C O(log n) - Logarithmic time

D O(n^2) - Quadratic time

💡 Hint

Deleting the last element usually just reduces the size counter.

Deleting the last element in a dynamic array is done by reducing the size variable, which is a constant time operation.