GATE CS 2016 Set 1 Q35 — Programming in C

To find the output of the program, we need to trace the execution of count(3). Note that d is a static variable, which means it is initialized only once (at the start of the program) and retains its value across all recursive function calls.

Step-by-Step Trace:

1. First Call: count(3) (where $n = 3$)
   • d is initialized to $1$.
   • Prints $n$ and $d$: 3 and 1.
     Current Output: 31
   • Increments d to $2$.
   • Since $n > 1$ ($3 > 1$), it calls count(2).
2. Second Call: count(2) (where $n = 2$)
   • d is currently $2$.
   • Prints $n$ and $d$: 2 and 2.
     Current Output: 3122
   • Increments d to $3$.
   • Since $n > 1$ ($2 > 1$), it calls count(1).
3. Third Call: count(1) (where $n = 1$)
   • d is currently $3$.
   • Prints $n$ and $d$: 1 and 3.
     Current Output: 312213
   • Increments d to $4$.
   • Since $n > 1$ ($1 > 1$) is false, it skips the recursive call.
   • Prints d: 4.
     Current Output: 3122134
   • count(1) finishes and returns to count(2).
4. Resuming count(2)
   • Prints d: Since d is static and currently $4$, it prints 4.
     Current Output: 31221344
   • count(2) finishes and returns to count(3).
5. Resuming count(3)
   • Prints d: Since d is static and currently $4$, it prints 4.
     Current Output: 312213444
   • count(3) finishes.

Thus, the final output is 3 1 2 2 1 3 4 4 4.