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GATE CSE 2026 Session 1 Q39: Recursive length of a non-empty singly linked list

Question

Consider the following code snippet in C language that computes the number of nodes in a non-empty singly linked list pointed to by the pointer variable head.

struct node{
  int elt;
  struct node *next;
};
int getListSize (struct node *head)
{
  if( E1 ) return 1;
  return E2;
}

Which one of the following options gives the correct replacements for the expressions E1 and E2?

Try it: multiple choice: exactly one correct option

Select one option
Wrong answer costs 2/3 mark in GATE.
Show answer and explanation

Answer: B (official GATE 2026 final answer key)

Concept used: Recursion on a non-empty list: base case is the last node, which counts as 1.

First step: Returning 1 is right only when head is the last node, i.e. head->next == NULL; the recursion must move to head->next.

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Source: official GATE 2026 Session 1 CS question paper and final answer key, organised by IIT Guwahati. Question paper · Answer key

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