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Programming and Data Structures · Recursion
Official IIT answer key · IIT Kanpur · Audited Aug 2026
GATE CSE 2015 Set 2 Q11 · NAT · 1 mark
int fun(int n) {
int x=1, k;
if (n==1) return x;
for (k=1; k<n; ++k)
x = x + fun(k) * fun(n-k);
return x;
}
The return value of fun(5) is _______.Key concept
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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 following C function. int fun(int n) int x=1, k; if (n==1) return x; for (k=1; k The return value of fun(5) is …
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