Factorial Using Recursion in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to return 1 when n is 0 in the factorial function.

DSA C

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

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A1

B0

C-1

Dn

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 instead of 0 as the base case condition.

Not having a base case causing infinite recursion.

The factorial of 0 is defined as 1, so the base case checks if n is 0.

2fill in blank

medium

Complete the recursive call to calculate factorial of n-1.

DSA C

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

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An - 1

Bn + 1

Cn

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using n + 1 causing infinite recursion.

Using n causing no progress towards base case.

The factorial function calls itself with n-1 to reduce the problem size step by step.

3fill in blank

hard

Fix the error in the main function to correctly call factorial and print the result.

DSA C

#include <stdio.h>

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

int main() {
    int num = 5;
    int result = factorial([1]);
    printf("Factorial of %d is %d\n", num, result);
    return 0;
}

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Anum

Bresult

C5

Dfactorial

Attempts:

3 left

💡 Hint

Common Mistakes

Passing result instead of num to factorial.

Passing the function name factorial instead of a number.

The factorial function should be called with the variable num to calculate factorial of 5.

4fill in blank

hard

Fill both blanks to complete the factorial function with proper base case and recursive call.

DSA C

int factorial(int n) {
    if (n == [1]) {
        return [2];
    }
    return n * factorial(n - 1);
}

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A0

B1

Cn

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Returning n instead of 1 in base case.

Checking for n == 1 instead of n == 0.

The base case checks if n is 0 and returns 1, which is the factorial of 0.

5fill in blank

hard

Fill all three blanks to create a recursive factorial function with base case and recursive step.

DSA C

int factorial(int [1]) {
    if ([2] == 0) {
        return [3];
    }
    return [2] * factorial([2] - 1);
}

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

An

C1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names inconsistently.

Returning 0 instead of 1 in base case.

The function parameter is n, the base case checks if n is 0, and returns 1 as factorial of 0.