QUESTION
Given a linked list, print reverse of it using a recursive function. For example, if the given linked list is 1->2->3->4, then output should be 4->3->2->1.
“TESTCASE_1”: “5\n5 4 4 3 2\n###—###SEPERATOR—###—\n2 3 4 4 5”, “TESTCASE_2”: “6 \n1 1 1 5 6 9\n###—###SEPERATOR—###—\n9 6 5 1 1 1”, “TESTCASE_3”: “4\n2 1 4 3\n###—###SEPERATOR—###—\n3 4 1 2”, “TESTCASE_4”: “7\n1 2 6 3 9 4 5\n###—###SEPERATOR—###—\n5 4 9 3 6 2 1”, “TESTCASE_5”: “0\n###—###SEPERATOR—###—\n0
ANSWER
#include<stdio.h>
#include<stdlib.h>
struct Node
{
int data;
struct Node* next;
};
static void reverse(struct Node** head_ref)
{
struct Node* prev = NULL;
struct Node* current = *head_ref;
struct Node* next = NULL;
while (current != NULL)
{
next = current->next;
current->next = prev;
prev = current;
current = next;
}
*head_ref = prev;
}
/* Function to push a node */
void push(struct Node** head_ref, int new_data)
{
/* allocate node */
struct Node* new_node =
(struct Node*) malloc(sizeof(struct Node));
/* put in the data */
new_node->data = new_data;
/* link the old list off the new node */
new_node->next = (*head_ref);
/* move the head to point to the new node */
(*head_ref) = new_node;
}
/* Function to print linked list */
void printList(struct Node *head)
{
struct Node *temp = head;
while(temp != NULL)
{
printf("%d ", temp->data);
temp = temp->next;
}
}
/* Driver program to test above function*/
int main()
{
/* Start with the empty list */
struct Node* head = NULL;
int n,i;
scanf("%d",&n);
int arr[n];
for(i=0;i<n;i++)
scanf("%d",&arr[i]);
for(i=n-1;i>=0;i--)
push(&head, arr[i]);
reverse(&head);
printList(head);
return 0;
}