AMU 2026 — Computer PYQ

The program tracks how many times the recursive function calc(int a, int b) is called using a global variable named counter. Every time calc() is entered, counter increments by $1$ via the line counter++;.

Let us trace the execution calls starting from the main() function:

1. Initial Call from main():

   • calc(4, 81) is called.

   • counter increments from $0$ to $1$.

   • Check base condition: Is $b<mark>3$? Here $81</mark>3$ is False.

   • It enters the else block and triggers a recursive call: calc(4, 81/3) which is calc(4, 27).

2. Second Recursive Call:

   • calc(4, 27) is executed.

   • counter increments from $1$ to $2$.

   • Check base condition: Is $27==3$? False.

   • Triggers the next recursive call: calc(4, 27/3) which is calc(4, 9).

3. Third Recursive Call:

   • calc(4, 9) is executed.

   • counter increments from $2$ to $3$.

   • Check base condition: Is $9==3$? False.

   • Triggers the next recursive call: calc(4, 9/3) which is calc(4, 3).

4. Fourth Recursive Call (Base Case Reached):

   • calc(4, 3) is executed.

   • counter increments from $3$ to $4$.

   • Check base condition: Is $3==3$? True.

   • The condition matches, so it returns $(4\times 4\times 4)=64$ directly without calling itself further.

5. Unwinding the Stack:

   • The functions return their values back up the call stack sequentially, but no more increments to counter happen.

   • Control returns to main().

6. Final Print:

   • printf("%d", counter); prints the final state of the global variable counter, which is 4.