Repeated_element_removing_LL.c

#include <stdio.h>
#include <stdlib.h>

/* Link list node */

struct Node
{

    int data;

    struct Node *next;
};

/* The function removes duplicates from a sorted list */

void removeDuplicates(struct Node *head)
{

    /* Pointer to traverse the linked list */

    struct Node *current = head;

    /* Pointer to store the next pointer of a node to be deleted*/

    struct Node *next_next;

    /* do nothing if the list is empty */

    if (current == NULL)

        return;

    /* Traverse the list till last node */

    while (current->next != NULL)

    {

        /* Compare current node with next node */

        if (current->data == current->next->data)

        {

            /* The sequence of steps is important*/

            next_next = current->next->next;

            free(current->next);

            current->next = next_next;
        }

        else /* This is tricky: only advance if no deletion */

        {

            current = current->next;
        }
    }
}

/* UTILITY FUNCTIONS */
/* Function to insert a node at the beginning of the linked list */

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 nodes in a given linked list */

void printList(struct Node *node)
{

    while (node != NULL)

    {

        printf("%d ", node->data);

        node = node->next;
    }
}

/* Driver program to test above functions*/

int main()
{

    /* Start with the empty list */

    struct Node *head = NULL;
    int n;
    scanf("%d", &n);
    int arr[n];
    for (int i = 0; i < n; i++)
    {
        scanf("%d", &arr[i]);
        push(&head, arr[i]);
    }

    /* Let us create a sorted linked list to test the functions

     Created linked list will be 11->11->11->13->13->20 */

    printf("\n Linked list before duplicate removal  ");

    printList(head);

    /* Remove duplicates from linked list */

    removeDuplicates(head);

    printf("\n Linked list after duplicate removal ");

    printList(head);
    return 0;
}