Recursion: A Comprehensive Guide for Beginners

Question 1

What is a potential downside to using recursion?

Accepted Answer

Increased risk of stack overflows

Answer

Increased code clarity

Answer

Improved efficiency

Answer

Simplified problem-solving

Question 2

When using recursion, which of these issues can potentially occur?

Accepted Answer

Uncontrolled recursion

Accepted Answer

Stack overflow

Answer

Compilation errors

Question 3

In a recursive function, the base case represents:

Accepted Answer

A stopping point where the problem can be solved without further recursive calls

Answer

A condition that makes the function call itself indefinitely

Answer

A special case that requires a different solution than the recursive calls

Question 4

Identify the function that is NOT a recursive function:

Accepted Answer

int add(int a, int b)

Answer

int factorial(int n)

Answer

int power(int base, int exponent)

Answer

int fibonacci(int n)

Question 5

The purpose of a recursive call is to:

Accepted Answer

Break down a problem into smaller subproblems

Answer

Store data in a temporary memory location

Answer

Halt the execution of the function

Answer

Return a result to the calling function

Question 6

Which of the following represents a valid recursive definition for the Fibonacci sequence?

Accepted Answer

F(0) = 0, F(1) = 1, F(n) = F(n-1) + F(n-2)

Answer

F(0) = 0, F(1) = 1, F(n) = F(n-1) - F(n-2)

Answer

F(0) = 1, F(1) = 1, F(n) = F(n-1) * F(n-2)

Answer

F(0) = 1, F(1) = 1, F(n) = F(n-1) + F(n+1)

Question 7

In recursion, direct recursion occurs when:

Accepted Answer

A function calls itself directly

Answer

A function calls another function that eventually calls the original function

Answer

A function calls itself multiple times in a row

Question 8

Which of the following statements accurately defines the base case for the factorial function?

Accepted Answer

When the input number (n) is equal to 0

Answer

When the input number (n) is greater than 1

Answer

When the input number (n) is 1

Answer

When the input number (n) is negative

Question 9

What is the central principle behind the technique of recursion?

Accepted Answer

A function's ability to call itself

Answer

Multiple arguments being passed to a function

Answer

Controlling program flow with conditional statements

Answer

Repetitive execution of instructions using loops

Question 10

What is the role of a base case in a recursive function?

Accepted Answer

To terminate the recursive process

Answer

To initiate the recursive process

Answer

To store intermediate results of recursion

Answer

To set the initial parameters for recursion

Question 11

Which of the following scenarios best exemplifies the appropriate use of recursion?

Accepted Answer

Solving problems that exhibit a recursive structure

Answer

Searching a database using linear search

Answer

Storing data in a linked list

Answer

Performing numerical calculations using arithmetic operators

Question 12

What is the defining characteristic of the Fibonacci sequence?

Accepted Answer

A sequence where each term is the sum of the two preceding terms

Answer

A sequence where each term is the square of the preceding term

Answer

A sequence where each term is the factorial of the preceding term

Question 13

Which recursive algorithm accurately calculates the factorial of a given number?

Accepted Answer

A recursive function that decrements the input number until it reaches the base case

Answer

A recursive function that squares the input number at each step

Answer

A recursive function that multiplies the input number by 2 at each step

Question 14

Identify the characteristic of a non-tail recursive function:

Accepted Answer

The recursive call is not the last action in the function

Answer

The function calls itself multiple times

Answer

The function calls another function before making the recursive call

Question 15

What is the fundamental principle of recursion?

Accepted Answer

A function calling itself

Answer

A function returning its own value

Answer

A function being called from multiple places

Answer

A function iterating over a collection

Question 16

What primary advantage does recursion offer?

Accepted Answer

Concise and elegant problem-solving

Answer

Reduced memory usage

Answer

Improved code performance

Answer

Enhanced code readability

Question 17

Within a recursive function, what is the purpose of the base case?

Accepted Answer

To terminate the recursion

Answer

To initiate the recursion

Answer

To determine the return value of the function

Question 18

Which of the following is NOT a potential challenge associated with recursion?

Accepted Answer

Limited memory usage

Answer

Stack overflow

Answer

Debugging difficulties

Answer

Code complexity

Question 19

Define a tail recursive function:

Accepted Answer

A function where the recursive call is the final action performed

Answer

A function where the recursive call is performed multiple times

Answer

A function where the recursive call is the first action performed

Question 20

Explain the distinction between direct and indirect recursion:

Accepted Answer

In direct recursion, the function calls itself directly, while in indirect recursion, it calls itself through another function

Answer

In direct recursion, the function calls itself multiple times, while in indirect recursion, it calls itself only once

Question 21

In a factorial function implemented recursively, what condition defines the base case that stops the recursive calls?

Accepted Answer

n == 0

Answer

n > 0

Answer

n == 1

Answer

n != 0

Question 22

What is the time complexity of a recursive factorial function? (e.g., f(n) = { if (n == 0) { return 1; } else { return n * f(n - 1); } })

Accepted Answer

O(n)

Answer

O(log n)

Answer

O(n^2)

Answer

O(2^n)

Question 23

Which of these code snippets represents a recursive approach to calculating the Fibonacci sequence?

Accepted Answer

fib(n) { if (n == 0 || n == 1) { return n; } else { return fib(n - 1) + fib(n - 2); } }

Answer

fib(n) { while (n > 1) { n = n - 1; } return n; }

Answer

fib(n) { for (i = 0; i < n; i++) { fib[i] = fib[i - 1] + fib[i - 2]; } return fib[n - 1]; }

Question 24

What is the primary difference between direct and indirect recursion?

Accepted Answer

Direct recursion involves a function calling itself directly, while indirect recursion uses multiple functions where one function calls another that eventually calls the original function.

Answer

Direct recursion is more efficient than indirect recursion.

Question 25

What is the fundamental principle behind recursion?

Accepted Answer

A function breaks down a problem into smaller, self-similar subproblems, solving each subproblem recursively and combining the results to solve the original problem.

Answer

A method of storing data in a hierarchical structure.

Answer

A loop that iterates through a predefined set of instructions.

Question 26

What are the two critical components of a well-structured recursive function?

Accepted Answer

Base case and recursive case.

Answer

Function arguments and return values.

Answer

Loop counter and condition.

Answer

Data structure and algorithm.

Question 27

What is the primary purpose of the base case in a recursive function?

Accepted Answer

To provide a stopping condition, preventing infinite recursion and ensuring the function eventually terminates.

Answer

To initiate the recursive calls.

Answer

To store intermediate results.

Question 28

Imagine a recursive function that prints numbers from 1 to n. In what order are the numbers printed?

Accepted Answer

The function recursively prints numbers from 1 to n-1, and then prints n after the recursive calls complete.

Answer

The function prints n first and then recursively prints numbers from 1 to n-1.

Question 29

In a recursive function that calculates the sum of all numbers from 1 to n, which part represents the recursive case?

Accepted Answer

return n + sum(n-1)

Answer

return 1 + sum(n-1)

Answer

return n

Answer

return sum(n-1)

Question 30

Which data structure is commonly used to model the behavior of the call stack during recursion?

Accepted Answer

Stack

Answer

Heap

Answer

Tree

Answer

Queue

Question 31

Which of the following is NOT a common application of recursion?

Accepted Answer

Performing mathematical operations like addition or subtraction.

Answer

Parsing text data.

Answer

Generating fractals.

Question 32

Which of the following is NOT a property of a recursive function?

Accepted Answer

It can terminate without returning a value.

Answer

It calls itself.

Answer

It can be used to solve complex problems in a simple manner.

Answer

It reduces the problem size with each iteration.

Question 33

What is the base case in the following recursive function? `factorial(n) = n * factorial(n-1)`

Accepted Answer

n = 0

Answer

n = 1

Answer

n > 1

Answer

n < 0

Question 34

Which of the following problems is most suitable to be solved using recursion?

Accepted Answer

Finding all the permutations of a string.

Answer

Sorting a list of numbers.

Answer

Converting a decimal number to binary.

Answer

Searching for a specific element in an array.

Question 35

What is the time complexity of the following recursive function? `fibonacci(n) = fibonacci(n-1) + fibonacci(n-2)`

Accepted Answer

Exponential (2^n)

Answer

Quadratic (n^2)

Answer

Linear (n)

Answer

Logarithmic (log n)

Question 36

What is the purpose of memoization in recursion?

Accepted Answer

To store the results of previous function calls to avoid redundant calculations.

Answer

To increase the efficiency of recursive functions.

Answer

To terminate the recursion when a certain condition is met.

Question 37

Which of the following is a common application of recursive backtracking algorithms?

Accepted Answer

Finding all possible solutions to a problem.

Answer

Converting a number from one base to another.

Answer

Sorting a list of elements.

Answer

Searching for a specific value in a dataset.

Question 38

What is the difference between direct and indirect recursion?

Accepted Answer

In direct recursion, the function calls itself, while in indirect recursion, the function calls another function that eventually calls the original function.

Answer

Direct recursion is iterative, while indirect recursion is non-iterative.

Question 39

Which of the following programming languages does NOT support recursion?

Accepted Answer

C

Answer

Python

Answer

Java

Answer

JavaScript

Question 40

What is a potential advantage of using recursion over iteration?

Accepted Answer

It can lead to more concise and elegant code in some cases.

Answer

It is easier to debug recursive code.

Answer

It always results in more efficient algorithms.

Question 41

What is the purpose of the base case in a recursive function?

Accepted Answer

To end the recursion and return a value

Answer

To pass data between recursive calls

Answer

To determine the number of times the function will call itself

Answer

To define the starting point of the recursion

Question 42

Which of the following is NOT a benefit of using recursion?

Accepted Answer

Improved code readability

Answer

Reduced code complexity

Answer

Easier to debug

Answer

Faster execution time