Data Structure Questions and Answers – Factorial using Recursion

This set of Data Structure Multiple Choice Questions & Answers (MCQs) focuses on “Factorial using Recursion”.

1. In general, which of the following methods isn’t used to find the factorial of a number?
a) Recursion
b) Iteration
c) Dynamic programming
d) Non iterative / recursive
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2. Which of the following recursive formula can be used to find the factorial of a number?
a) fact(n) = n * fact(n)
b) fact(n) = n * fact(n+1)
c) fact(n) = n * fact(n-1)
d) fact(n) = n * fact(1)
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3. Consider the following iterative implementation to find the factorial of a number. Which of the lines should be inserted to complete the below code?

int main()
{
    int n = 6, i;
    int fact = 1;
    for(i=1;i<=n;i++)
      _________;
    printf("%d",fact);
    return 0;
}

a) fact = fact + i
b) fact = fact * i
c) i = i * fact
d) i = i + fact
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4. Consider the following recursive implementation to find the factorial of a number. Which of the lines should be inserted to complete the below code?

int fact(int n)
{
     if(_________)
        return 1;
     return n * fact(n - 1);
}
int main()
{
      int n = 5;
      int ans = fact(n);
      printf("%d",ans);
      return 0;
}

a) n = 0
b) n != 0
c) n == 0
d) n == 1
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5. The time complexity of the following recursive implementation to find the factorial of a number is ________

int fact(int n)
{
     if(_________)
        return 1;
     return n * fact(n - 1);
}
int main()
{
      int n = 5;
      int ans = fact(n);
      printf("%d",ans);
      return 0;
}

a) O(1)
b) O(n)
c) O(n²)
d) O(n³)
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6. What is the space complexity of the following recursive implementation to find the factorial of a number?

int fact(int n)
{
     if(_________)
        return 1;
     return n * fact(n - 1);
}
int main()
{
      int n = 5;
      int ans = fact(n);
      printf("%d",ans);
      return 0;
}

a) O(1)
b) O(n)
c) O(n²)
d) O(n³)
View Answer

7. Consider the following recursive implementation to find the factorial of a number. Which of the lines is the base case?

int fact(int n)
{
     if(n == 0)
        return 1;
     return n * fact(n - 1);
}
int main()
{
      int n = 5;
      int ans = fact(n);
      printf("%d",ans);
      return 0;
}

a) return 1
b) return n * fact(n-1)
c) if(n == 0)
d) if(n == 1)
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8. What is the output of the following code?

int fact(int n)
{
      if(n == 0)
        return 1;
      return n * fact(n - 1);
}
int main()
{
      int n = 0;
      int ans = fact(n);
      printf("%d",ans);
      return 0;
}

a) 0
b) 1
c) 2
d) 3
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9. What is the output of the following code?

int fact(int n)
{
      if(n == 0)
        return 1;
      return n * fact(n - 1);
}
int main()
{
      int n = 1;
      int ans = fact(n);
      printf("%d",ans);
      return 0;
}

a) 0
b) 1
c) 2
d) 3
View Answer

10. How many times will the function fact() be called when the following code is executed?

int fact(int n)
{
      if(n == 0)
        return 1;
      return n * fact(n - 1);
}
int main()
{
      int n = 5;
      int ans = fact(n);
      printf("%d",ans);
      return 0;
}

a) 4
b) 5
c) 6
d) 7
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11. What is the output of the following code?

int fact(int n)
{
      if(n == 0)
        return 1;
      return n * fact(n - 1);
}
int main()
{
      int n = 5;
      int ans = fact(n);
      printf("%d",ans);
      return 0;
}

a) 24
b) 120
c) 720
d) 1
View Answer

Sanfoundry Global Education & Learning Series – Data Structures & Algorithms.

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