Test: Recursion- 2 - Computer Science Engineering (CSE) MCQ

Fun(2)
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2*fun(3)
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2*fun(4)
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4 After tree evaluation we get 16
So, C is the correct answer

The function fun() calculates and returns ((1 + 2 … + x-1 + x) +y) which is x(x+1)/2 + y.

The function mainly prints binary representation in reverse order.

The function adds x to itself y times which is x*y.

The function multiplies x to itself y times which is x^y.

The call foo(345, 10) returns sum of decimal digits (because r is 10) in the number n. Sum of digits for 345 is 3 + 4 + 5 = 12.

foo(513, 2) will return 1 + foo(256, 2). All subsequent recursive calls (including foo(256, 2)) will return 0 + foo(n/2, 2) except the last call foo(1, 2). The last call foo(1, 2) returns 1. So, the value returned by foo(513, 2) is 1 + 0 + 0…. + 0 + 1. The function foo(n, 2) basically returns sum of bits (or count of set bits) in the number n.

f() is a recursive function which adds f(a+1, n-1) to *a if *a is even. If *a is odd then f() subtracts f(a+1, n-1) from *a. See below recursion tree for execution of f(a, 6).

So, the final returned value is 12 + (7 – (13 – (4 + (11 – (6 + 0))))) = 15

Every function call is stored in the stack memory. In this case, there is no terminating condition(base case). So, my_recursive_function() will be called continuously till the stack overflows and there is no more space to store the function calls. At this point of time, the program will stop abruptly.

When j is 50, the function would call itself again and again as neither i nor j is changed inside the recursion.

count(3) will print value of n and d. So 3 1 will be printed and d will become 2.
Then count(2) will be called. It will print value of n and d.
So 2 2 will be printed and d will become 3.
Then count(1) will be called. It will print value of n and d.
So 1 3 will be printed and d will become 4.
Now count(1) will print value of d which is 4. count(1) will finish its execution.
Then count(2) will print value of d which is 4.
Similarly, count(3) will print value of d which is 4.
So series will be A.

The function terminates for all values having a factor of 2 {(2.x)2==0}
So, (i) is false and (ii) is TRUE.
Let n = 3, it will terminate in 2nd iteration.
Let n=5, it will go like 5 - 14 - 7 - 20 - 10 - 5 – and now it will repeat.
And any number with a factor of 5 and 2, there are infinite recursions possible.
So, (iv) is TRUE and (iii) is false.