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+13 votes

Consider the following recursive C function that takes two arguments.

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 $\text{foo}$ when it is called as $\text{foo(513, 2)}$?

  1. $9$
  2. $8$
  3. $5$
  4. $2$
in Algorithms by
edited by | 1.5k views
same Q appeared in ISRO 2020

3 Answers

+21 votes
Best answer
The function returns the sum of digits in a binary representation of the given number

so $1+0+0+0+0+0+0+0+0+1 = 2$

Correct Answer: $D$
edited by
if you simulate this program with different values of n and r, notice that this function foo(n,r) gives the sum of digits of n(when it is converted to base r).

Like if n=513, r=14 then $(513)_{10}=(289)_{14}$ and 2+8+9=19 and this is the output of the program.
+9 votes

Final return value is 2 So option d

0 votes

∴ 1+0+0+0+0+0+0+0+0+1+0 = 2


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