Recursion Base Case and Recursive Case in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the base case for the factorial function.

DSA C

int factorial(int n) {
    if (n == [1]) {
        return 1;
    }
    return n * factorial(n - 1);
}

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

A0

B1

C-1

Dn

Attempts:

3 left

💡 Hint

Common Mistakes

Using n == 1 as base case instead of n == 0

Not defining a base case causing infinite recursion

The base case for factorial is when n is 0, factorial(0) = 1.

2fill in blank

medium

Complete the code to correctly call the recursive case in the factorial function.

DSA C

int factorial(int n) {
    if (n == 0) {
        return 1;
    }
    return n [1] factorial(n - 1);
}

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

A/

B+

C-

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition instead of multiplication

Using division or subtraction incorrectly

The recursive case multiplies n by factorial of (n-1).

3fill in blank

hard

Fix the error in the recursive Fibonacci function base case.

DSA C

int fibonacci(int n) {
    if (n == [1] || n == 1) {
        return n;
    }
    return fibonacci(n - 1) + fibonacci(n - 2);
}

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

A1

B2

C0

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using n == 2 as base case

Missing the base case for n == 0

The base case for Fibonacci includes n == 0 and n == 1.

4fill in blank

hard

Fill both blanks to complete the recursive sum function that sums numbers from n down to 1.

DSA C

int sum(int n) {
    if (n [1] 0) {
        return 0;
    }
    return n [2] sum(n - 1);
}

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

A<=

B>

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong comparison operator in base case

Using subtraction instead of addition in recursive case

The base case checks if n is less than or equal to 0, then returns 0. The recursive case adds n to sum(n-1).

5fill in blank

hard

Fill all three blanks to complete the recursive function that counts down from n to 1 and prints each number.

DSA C

void countdown(int n) {
    if (n [1] 0) {
        return;
    }
    printf("%d\n", n);
    countdown(n [2] 1);
    printf("[3]\n");
}

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

A<=

B-

C+

DDone

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong comparison operator in base case

Using addition instead of subtraction in recursive call

Not printing the completion message

The base case checks if n is less than or equal to 0. The recursive call decreases n by 1. After recursion, it prints "Done".