Programming and Data Structures · Recursion
Official IIT answer key · IIT Roorkee · Audited Aug 2026
GATE CSE 2026 Set 1 Q61 · NAT · 2 marks
int bar(int n) {
if (n == 1) return 0;
else return 1 + bar(n/2);
}
int foo(int n) {
if (n == 1) return 1;
else return 1 + foo(bar(n));
}
The smallest positive integer n for which foo(n) returns 5 is ________. (answer in integer)
Note: Ignore syntax errors (if any) in the function.Key concept
No account needed
Sit 5 related RecursionPYQs as a guest. We'll score the set and show which traps cost marks — sign in only if you want to save the run.
Topic notes
GATE tests Recursion primarily through direct execution tracing of recursive C code snippets, stack-unwinding behavior (pre-order vs. post-order execution), and termination/infinite recursion analysis. Questions frequently incorporate static variables, pointer/reference aliasing, mutual recursion, and tree/array traversals to test whether candidates can systematically maintain call frames. In recent years, the focus has expanded from standard tracing to higher-order mathematical characterizations (e.g., finding the smallest input or maximum output value of composed recurrences).
Full Recursion guide →Consider the recursive functions represented by the following code segment: int bar(int n) if (n == 1) return 0; else return 1 + bar(n/2); int foo(int n) if (n == 1) return 1; else return 1 + foo(bar(n)); The smallest positive integer n for which foo(n) returns 5 is … (answer in integer) Note: Ignore syntax errors (if any) in the function.
Topic-wise GATE CS PYQs with verified steps
Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.