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GATE | GATE CS 2011 | Question 49

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Consider the same 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;
}


What is the return value of the function foo when it is called as foo(513, 2)?

(A)

9

(B)

8

(C)

5

(D)

2



Answer: (D)

Explanation:

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.

Hence (D) is the correct Answer.


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Last Updated : 28 Jun, 2021
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