Fibonacci Using Recursion in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the base case for Fibonacci recursion.

DSA C

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

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

A1

B0

C2

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 instead of 0 as the base case.

Not defining a base case causing infinite recursion.

The base case for Fibonacci recursion is when n is 0, return 0.

2fill in blank

medium

Complete the code to define the second base case for Fibonacci recursion.

DSA C

int fibonacci(int n) {
    if (n == 0) {
        return 0;
    } else if (n == [1]) {
        return 1;
    }
    return fibonacci(n - 1) + fibonacci(n - 2);
}

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

A2

B3

C-1

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 instead of 1 for the second base case.

Missing the second base case causing incorrect results.

The second base case is when n is 1, return 1.

3fill in blank

hard

Fix the error in the recursive call to correctly calculate Fibonacci.

DSA C

int fibonacci(int n) {
    if (n == 0) {
        return 0;
    } else if (n == 1) {
        return 1;
    }
    return fibonacci(n [1] 1) + fibonacci(n - 2);
}

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

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using + instead of - causing infinite recursion.

Using * or / which are incorrect for Fibonacci.

The recursive call should subtract 1 from n to get the previous Fibonacci number.

4fill in blank

hard

Fill both blanks to complete the main function that prints Fibonacci numbers up to n.

DSA C

#include <stdio.h>

int fibonacci(int n);

int main() {
    int n = 5;
    for (int i = [1]; i [2] n; i++) {
        printf("%d ", fibonacci(i));
    }
    return 0;
}

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

A0

B<=

C<

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Starting loop at 1 missing the first Fibonacci number.

Using <= causing one extra number to print.

The loop starts at 0 and runs while i is less than n to print Fibonacci numbers from 0 to n-1.

5fill in blank

hard

Fill all three blanks to complete the recursive Fibonacci function with correct base cases and recursive calls.

DSA C

int fibonacci(int n) {
    if (n == [1]) {
        return 0;
    } else if (n == [2]) {
        return 1;
    }
    return fibonacci(n [3] 1) + fibonacci(n - 2);
}

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

A0

B1

C-

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up base case values.

Using addition instead of subtraction in recursive calls.

The base cases are n == 0 returning 0, n == 1 returning 1, and recursive calls subtract 1 and 2 from n.