Programming and Data Structures · Recursion
Official IIT answer key · IIT Guwahati · Audited Aug 2026
GATE CSE 2025 Set 1 Q61 · NAT · 2 marks
#include <stdio.h>
int foo(int S[],int size){
if(size == 0) return 0;
if(size == 1) return 1;
if(S[0] != S[1]) return 1+foo(S+1,size-1);
return foo(S+1,size-1);
}
int main(){
int A[]={0,1,2,2,2,0,0,1,1};
printf("%d",foo(A,9));
return 0;
}
The value printed by the given C program is ________ . (Answer in integer)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 →#include int foo(int S[],int size) if(size == 0) return 0; if(size == 1) return 1; if(S[0] != S[1]) return 1+foo(S+1,size-1); return foo(S+1,size-1); int main() int A[]=0,1,2,2,2,0,0,1,1; printf("%d",foo(A,9)); return 0; The value printed by the given C program is … (Answer in integer)
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