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Software Development Exam  >  Software Development Test  >  DSA in C++  >  Test: Recursion - 1 - Software Development MCQ

Recursion - 1 - Free MCQ Practice Test with solutions, Software Development


MCQ Practice Test & Solutions: Test: Recursion - 1 (15 Questions)

You can prepare effectively for Software Development DSA in C++ with this dedicated MCQ Practice Test (available with solutions) on the important topic of "Test: Recursion - 1". These 15 questions have been designed by the experts with the latest curriculum of Software Development 2026, to help you master the concept.

Test Highlights:

  • - Format: Multiple Choice Questions (MCQ)
  • - Duration: 30 minutes
  • - Number of Questions: 15

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Test: Recursion - 1 - Question 1
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Which of the following best defines recursion?

Detailed Solution: Question 1

Recursion involves breaking a problem into smaller subproblems that are of the same type as the original problem. It allows the problem to be solved by solving smaller instances of the same problem.

Test: Recursion - 1 - Question 2
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In recursion, what is the base case?

Detailed Solution: Question 2

The base case is a condition in a recursive function that specifies when the recursion should stop. It is the case where the problem is solved directly without further recursion. Without a base case, the recursive function would continue calling itself indefinitely, resulting in infinite recursion.

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Test: Recursion - 1 - Question 3
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Which of the following is NOT a characteristic of recursive functions?

Detailed Solution: Question 3

Recursive functions do not always involve the use of loops. In fact, recursive functions are an alternative to iterative loops. Recursion involves calling the same function within itself, allowing the problem to be solved by dividing it into smaller subproblems.

Test: Recursion - 1 - Question 4
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What is the output of the following recursive function?

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

cout << factorial(5);

Detailed Solution: Question 4

The given code calculates the factorial of a number using recursion. The base case is when n is 0, in which case 1 is returned. Otherwise, the factorial is calculated as n multiplied by the factorial of n - 1. Therefore, factorial(5) would be equal to 5 * 4 * 3 * 2 * 1 = 120.

Test: Recursion - 1 - Question 5
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Which of the following problems can be solved using recursion?

Detailed Solution: Question 5

The Fibonacci sequence can be efficiently calculated using recursion. Each term in the sequence is the sum of the two preceding terms, and this pattern can be expressed recursively. Other problems mentioned, such as finding the maximum element in an array or sorting an array, can be solved more efficiently using other techniques like iteration.

Test: Recursion - 1 - Question 6
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What is the output of the following code?
#include <iostream>

void printNumbers(int n) {
    if (n > 0) {
        printNumbers(n - 1);
        cout << n << " ";
    }
}

printNumbers(5);

Detailed Solution: Question 6

The printNumbers function prints the numbers from n to 1 in descending order. It uses recursion to print the numbers in reverse order by first recursively calling itself with n - 1, and then printing n. The base case is when n is greater than 0. Therefore, the output of printNumbers(5) would be "5 4 3 2 1".

Test: Recursion - 1 - Question 7
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What is the output of the following code?

#include <iostream>

int power(int base, int exponent) {
    if (exponent == 0) {
        return 1;
    } else {
        return base * power(base, exponent - 1);
    }
}

cout << power(2, 4);

Detailed Solution: Question 7

The power function calculates the exponentiation of a base number. It uses recursion to multiply the base by itself exponent number of times. The base case is when exponent is 0, in which case 1 is returned. Otherwise, the result is calculated as base multiplied by power(base, exponent - 1). Therefore, power(2, 4) would be equal to 2 * 2 * 2 * 2 = 16.

Test: Recursion - 1 - Question 8
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What is the output of the following code?
#include <iostream>

bool isPalindrome(string str, int start, int end) {
    if (start >= end) {
        return true;
    } else if (str[start] != str[end]) {
        return false;
    } else {
        return isPalindrome(str, start + 1, end - 1);
    }
}

string str = "racecar";
cout << isPalindrome(str, 0, str.length() - 1);

Detailed Solution: Question 8

The isPalindrome function checks if a string is a palindrome using recursion. It compares the characters at the start and end indices of the string, recursively moving towards the center of the string. If the characters are not equal, it returns false. If the start index becomes greater than or equal to the end index, it means all characters have been compared and found to be equal, so it returns true. Therefore, the output of isPalindrome("racecar", 0, str.length() - 1) would be true.

Test: Recursion - 1 - Question 9
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What is the output of the following code?
#include <iostream>

void printSubset(int arr[], int size, int index, string subset) {
    if (index == size) {
        cout << subset << " ";
        return;
    }
    
    printSubset(arr, size, index + 1, subset + to_string(arr[index]) + " ");
    printSubset(arr, size, index + 1, subset);
}

int arr[] = {1, 2, 3};
printSubset(arr, 3, 0, "");

Detailed Solution: Question 9

The printSubset function prints all possible subsets of an array. It uses recursion to generate subsets by either including or excluding the current element at each step. The base case is when index is equal to size, in which case the current subset is printed. The function makes two recursive calls: one including the current element and another excluding it. Therefore, the output of printSubset(arr, 3, 0, "") would be "1 2 3 1 2 3".

Test: Recursion - 1 - Question 10
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What is the output of the following code?
#include <iostream>

void printSubsetSum(int arr[], int size, int index, int sum, string subset) {
    if (index == size) {
        if (sum == 0) {
            cout << subset << " ";
        }
        return;
    }
    
    printSubsetSum(arr, size, index + 1, sum - arr[index], subset + to_string(arr[index]) + " ");
    printSubsetSum(arr, size, index + 1, sum, subset);
}

int arr[] = {1, 2, 3};
printSubsetSum(arr, 3, 0, 3, "");

Detailed Solution: Question 10

The printSubsetSum function prints all subsets of an array that sum up to a given target sum. It uses recursion to generate subsets by either including or excluding the current element at each step. The base case is when index is equal to size and sum is 0, in which case the current subset is printed. The function makes two recursive calls: one including the current element and subtracting its value from the sum, and another excluding the current element. Therefore, the output of printSubsetSum(arr, 3, 3, "") would be "1 2 3".

Test: Recursion - 1 - Question 11
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What is the output of the following code?
#include <iostream>

int sumDigits(int n) {
    if (n == 0) {
        return 0;
    } else {
        return n % 10 + sumDigits(n / 10);
    }
}

cout << sumDigits(12345);

Detailed Solution: Question 11

The sumDigits function calculates the sum of digits of a given number using recursion. It adds the last digit of the number to the sum of the remaining digits, which is obtained by dividing the number by 10. The base case is when the number becomes 0, in which case the sum is 0. Therefore, the output of sumDigits(12345) would be 1 + 2 + 3 + 4 + 5 = 15.

Test: Recursion - 1 - Question 12
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What is the output of the following code?
#include <iostream>

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

cout << countPairs(5);

Detailed Solution: Question 12

The countPairs function calculates the number of pairs that can be formed by a given number of people using recursion. It subtracts 1 from the number of people and recursively calls itself with the reduced number until the base case is reached. The base case is when the number of people becomes 0, 1, or 2, in which case the count is 0. Therefore, the output of countPairs(5) would be 4 + 3 + 2 + 1 = 10.

Test: Recursion - 1 - Question 13
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What is the output of the following code?
#include <iostream>

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

cout << fibonacci(5);

Detailed Solution: Question 13

The fibonacci function calculates the nth Fibonacci number using recursion. It uses the property that each Fibonacci number is the sum of the two preceding numbers. The base case is when n is less than or equal to 1, in which case n is returned. Therefore, the output of fibonacci(5) would be the 5th Fibonacci number, which is 8.

Test: Recursion - 1 - Question 14
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What is the output of the following code?
#include <iostream>

int gcd(int a, int b) {
    if (b == 0) {
        return a;
    } else {
        return gcd(b, a % b);
    }
}

cout << gcd(24, 36);

Detailed Solution: Question 14

The gcd function calculates the greatest common divisor (GCD) of two numbers using recursion and the Euclidean algorithm. It divides a by b and recursively calls itself with b and the remainder of a divided by b until the base case is reached. The base case is when b becomes 0, in which case a is returned as the GCD. Therefore, the output of gcd(24, 36) would be the GCD of 24 and 36, which is 6.

Test: Recursion - 1 - Question 15
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What is the output of the following code?
#include <iostream>

int countSubsetSum(int arr[], int size, int sum) {
    if (sum == 0) {
        return 1;
    } else if (size == 0) {
        return 0;
    } else if (arr[size - 1] > sum) {
        return countSubsetSum(arr, size - 1, sum);
    } else {
        return countSubsetSum(arr, size - 1, sum) + countSubsetSum(arr, size - 1, sum - arr[size - 1]);
    }
}

int arr[] = {1, 2, 3};
cout << countSubsetSum(arr, 3, 3);

Detailed Solution: Question 15

The countSubsetSum function counts the number of subsets of an array that sum up to a given target sum using recursion. It makes two recursive calls: one including the current element and subtracting its value from the sum, and another excluding the current element. The base cases are when the sum becomes 0, in which case 1 is returned, or when the size becomes 0, in which case 0 is returned. Therefore, the output of countSubsetSum(arr, 3, 3) would be 4.

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This test contains 15 MCQs on Recursion - 1 with detailed solutions for each question. It is part of the DSA in C++ course on EduRev, designed to align with the current Software Development syllabus. Each solution explains not just the correct answer but also gives you an understanding of the topic — not just to attempt the question but also help you prepare for the exam with practice.

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