List of top Programming and Data Structures Questions on Linked Lists asked in GATE CS

Consider the problem of reversing a singly linked list. To take an example, given the linked list below, 

The reversed linked list should look like 

Which one of the following statements is TRUE about the time complexity of algorithms that solve the above problem in \( O(1) \) space?

Consider the following ANSI C program: 

#include <stdio.h> 
#include <stdlib.h> 
struct Node{ 
	int value; 
	struct Node *next; }; 
int main(){ 
	struct Node *boxE, *head, *boxN; int index = 0; 
	boxE = head = (struct Node *) malloc(sizeof(struct Node)); 
	head->value = index; 
	for (index = 1; index <= 3; index++){ 
		boxN = (struct Node *) malloc(sizeof(struct Node)); 
		boxE->next = boxN; 
		boxN->value = index; 
		boxE = boxN; } 
	for (index = 0; index <= 3; index++) { 
		printf("Value at index %d is %d\n", index, head->value); 
		head = head->next; 
		printf("Value at index %d is %d\n", index+1, head->value); } } 

Which one of the statements below is correct about the program?