Top MCQs on Recursion Algorithm with Answers (original) (raw)

Predict output of following program

C++ `

#include

int fun(int n) { if (n == 4) return n; else return 2 * fun(n + 1); }

int main() { std::cout << fun(2); return 0; }

C

#include <stdio.h>

int fun(int n) { if (n == 4) return n; else return 2*fun(n+1); }

int main() { printf("%d", fun(2)); return 0; }

Java

public class Main { public static int fun(int n) { if (n == 4) return n; else return 2 * fun(n + 1); }

public static void main(String[] args) {
    System.out.println(fun(2));
}

}

Python

def fun(n): if n == 4: return n else: return 2 * fun(n + 1)

print(fun(2))

JavaScript

function fun(n) { if (n === 4) return n; else return 2 * fun(n + 1); }

console.log(fun(2));

`

Consider the following recursive function fun(x, y). What is the value of fun(4, 3)

C++ `

int fun(int x, int y) { if (x == 0) return y; return fun(x - 1, x + y); }

C

int fun(int x, int y) { if (x == 0) return y; return fun(x - 1, x + y); }

Java

int fun(int x, int y) { if (x == 0) return y; return fun(x - 1, x + y); }

Python

def fun(x, y): if x == 0: return y return fun(x - 1, x + y)

JavaScript

function fun(x, y) { if (x === 0) return y; return fun(x - 1, x + y); }

`

What does the following function print for n = 25?

C++ `

#include using namespace std;

void fun(int n) { if (n == 0) return;

cout << n % 2;
fun(n / 2);

}

C

void fun(int n) { if (n == 0) return;

printf("%d", n%2); fun(n/2); }

Java

public class Main { public static void fun(int n) { if (n == 0) return;

    System.out.print(n % 2);
    fun(n / 2);
}

public static void main(String[] args) {
    fun(10); // Example call
}

}

Python

def fun(n): if n == 0: return

print(n % 2, end='')
fun(n // 2)

JavaScript

function fun(n) { if (n === 0) return;

process.stdout.write((n % 2).toString());
fun(Math.floor(n / 2));

}

`

What does the following function do?

C `

int fun(int x, int y) { if (y == 0) return 0; return (x + fun(x, y-1)); }

`

What does fun2() do in general?

C++ `

#include

int fun(int x, int y) { if (y == 0) return 0; return (x + fun(x, y-1)); }

int fun2(int a, int b) { if (b == 0) return 1; return fun(a, fun2(a, b-1)); }

C

int fun(int x, int y) { if (y == 0) return 0; return (x + fun(x, y-1)); }

int fun2(int a, int b) { if (b == 0) return 1; return fun(a, fun2(a, b-1)); }

Java

public class Main { public static int fun(int x, int y) { if (y == 0) return 0; return (x + fun(x, y - 1)); }

public static int fun2(int a, int b) {
    if (b == 0) return 1;
    return fun(a, fun2(a, b - 1));
}

public static void main(String[] args) {
    // Example usage
}

}

Python

def fun(x, y): if y == 0: return 0 return x + fun(x, y - 1)

def fun2(a, b): if b == 0: return 1 return fun(a, fun2(a, b - 1))

JavaScript

function fun(x, y) { if (y === 0) return 0; return x + fun(x, y - 1); }

function fun2(a, b) { if (b === 0) return 1; return fun(a, fun2(a, b - 1)); }

`

Output of following program?

C++ `

#include using namespace std;

void print(int n) { if (n > 4000) return; cout << n << " "; print(2 * n); cout << n << " "; }

int main() { print(1000); cin.get(); return 0; }

C

#include<stdio.h> void print(int n) { if (n > 4000) return; printf("%d ", n); print(2*n); printf("%d ", n); }

int main() { print(1000); getchar(); return 0; }

Java

public class Main { public static void print(int n) { if (n > 4000) return; System.out.print(n + " "); print(2 * n); System.out.print(n + " "); }

public static void main(String[] args) {
    print(1000);
}

}

Python

def print_numbers(n): if n > 4000: return print(n, end=' ') print_numbers(2 * n) print(n, end=' ')

print_numbers(1000)

JavaScript

function print(n) { if (n > 4000) return; process.stdout.write(n + ' '); print(2 * n); process.stdout.write(n + ' '); }

print(1000);

`

• 1000 2000 4000 4000 2000 1000

What does the following function do?

C++ `

int fun(unsigned int n) { if (n == 0 || n == 1) return n;

if (n % 3 != 0)
    return 0;

return fun(n / 3);

}

C

int fun(unsigned int n) { if (n == 0 || n == 1) return n;

if (n%3 != 0)
    return 0;

return fun(n/3);

}

Java

int fun(unsigned int n) { if (n == 0 || n == 1) return n;

if (n % 3 != 0)
    return 0;

return fun(n / 3);

}

Python

def fun(n): if n == 0 or n == 1: return n

if n % 3 != 0:
    return 0

return fun(n // 3)

JavaScript

function fun(n) { if (n === 0 || n === 1) return n;

if (n % 3 !== 0)
    return 0;

return fun(n / 3);

}

`

• It returns 1 when n is a multiple of 3, otherwise returns 0
• It returns 1 when n is a power of 3, otherwise returns 0
• It returns 0 when n is a multiple of 3, otherwise returns 1
• It returns 0 when n is a power of 3, otherwise returns 1

Predict the output of following program

C++ `

#include using namespace std;

int f(int n) { if(n <= 1) return 1; if(n % 2 == 0) return f(n / 2); return f(n / 2) + f(n / 2 + 1); }

int main() { cout << f(11); return 0; }

C

#include <stdio.h> int f(int n) { if(n <= 1) return 1; if(n%2 == 0) return f(n/2); return f(n/2) + f(n/2+1); }

int main() { printf("%d", f(11)); return 0; }

Java

public class Main { public static int f(int n) { if(n <= 1) return 1; if(n % 2 == 0) return f(n / 2); return f(n / 2) + f(n / 2 + 1); }

public static void main(String[] args) {
    System.out.println(f(11));
}

}

Python

def f(n): if n <= 1: return 1 if n % 2 == 0: return f(n // 2) return f(n // 2) + f(n // 2 + 1)

print(f(11))

JavaScript

function f(n) { if (n <= 1) return 1; if (n % 2 === 0) return f(n / 2); return f(Math.floor(n / 2)) + f(Math.floor(n / 2) + 1); }

console.log(f(11));

`

Predict the output:

C++ `

#include using namespace std;

void crazy(int n, int a, int b) { if (n <= 0) return; crazy(n - 1, a, b + n); cout << n << " " << a << " " << b << endl; crazy(n - 1, b, a + n); }

int main() { crazy(3, 4, 5); return 0; }

C

#include <stdio.h> void crazy(int n, int a, int b) { if (n <= 0) return; crazy(n - 1, a, b + n); printf("%d %d %d \n",n,a,b); crazy(n-1, b, a+n); }

int main() { crazy(3, 4, 5); return 0; }

Java

public class Crazy { public static void crazy(int n, int a, int b) { if (n <= 0) return; crazy(n - 1, a, b + n); System.out.println(n + " " + a + " " + b); crazy(n - 1, b, a + n); }

public static void main(String[] args) {
    crazy(3, 4, 5);
}

}

Python

def crazy(n, a, b): if n <= 0: return crazy(n - 1, a, b + n) print(n, a, b) crazy(n - 1, b, a + n) crazy(3, 4, 5)

JavaScript

function crazy(n, a, b) { if (n <= 0) return; crazy(n - 1, a, b + n); console.log(n, a, b); crazy(n - 1, b, a + n); }

crazy(3, 4, 5);

`

• 1 4 10
  2 4 8
  1 8 6
  3 4 5
  1 5 9
  2 5 7
  1 7 7
• 3 4 5
  1 4 10
  2 4 8
  1 8 6
  1 5 9
  2 5 7
  1 7 7

Consider the following recursive C++ function that takes two arguments

C++ `

unsigned int foo(unsigned int n, unsigned int r) { if (n > 0) return (n%r + foo (n/r, r )); else return 0; }

C

unsigned int foo(unsigned int n, unsigned int r) { if (n > 0) return (n % r + foo(n / r, r)); else return 0; }

Java

public class Main { public static int foo(int n, int r) { if (n > 0) return (n % r + foo(n / r, r)); else return 0; } }

Python

def foo(n, r): if n > 0: return (n % r + foo(n // r, r)) else: return 0

JavaScript

function foo(n, r) { if (n > 0) return (n % r + foo(Math.floor(n / r), r)); else return 0; }

`

What is the return value of the function foo when it is called foo(345, 10)?

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