/**
 * C program to delete middle node of Singly Linked List
 */

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

/* Structure of a node */
struct node
{
    int data;          // Data
    struct node *next; // Address
} *head;

/* Functions used in program */
void createList(int n);
void deleteMiddleNode(int position);
void displayList();

/*
 * Create a list of n nodes
 */
void createList(int n)
{
    struct node *newNode, *temp;
    int data, i;

    head = (struct node *)malloc(sizeof(struct node));

    /*
     * If unable to allocate memory for head node
     */
    if (head == NULL)
    {
        printf("Unable to allocate memory.");
    }
    else
    {
        /*
         * Read data of node from the user
         */
        printf("Enter the data of node 1: ");
        scanf("%d", &data);

        head->data = data; // Link the data field with data
        head->next = NULL; // Link the address field to NULL

        temp = head;

        /*
         * Create n nodes and adds to linked list
         */
        for (i = 2; i <= n; i++)
        {
            newNode = (struct node *)malloc(sizeof(struct node));

            /* If memory is not allocated for newNode */
            if (newNode == NULL)
            {
                printf("Unable to allocate memory.");
                break;
            }
            else
            {
                printf("Enter the data of node %d: ", i);
                scanf("%d", &data);

                newNode->data = data; // Link the data field of newNode with data
                newNode->next = NULL; // Link the address field of newNode with NULL

                temp->next = newNode; // Link previous node i.e. temp to the newNode
                temp = temp->next;
            }
        }

        printf("SINGLY LINKED LIST CREATED SUCCESSFULLY\n");
    }
}

/*
 * Delete middle node of the linked list
 */
void deleteMiddleNode(int position)
{
    int i;
    struct node *toDelete, *prevNode;

    if (head == NULL)
    {
        printf("List is already empty.");
    }
    else
    {
        toDelete = head;
        prevNode = head;

        for (i = 2; i <= position; i++)
        {
            prevNode = toDelete;
            toDelete = toDelete->next;

            if (toDelete == NULL)
                break;
        }

        if (toDelete != NULL)
        {
            if (toDelete == head)
                head = head->next;

            prevNode->next = toDelete->next;
            toDelete->next = NULL;

            /* Delete nth node */
            free(toDelete);

            printf("SUCCESSFULLY DELETED NODE FROM MIDDLE OF LIST\n");
        }
        else
        {
            printf("Invalid position unable to delete.");
        }
    }
}

/*
 * Display entire list
 */
void displayList()
{
    struct node *temp;

    /*
     * If the list is empty i.e. head = NULL
     */
    if (head == NULL)
    {
        printf("List is empty.");
    }
    else
    {
        temp = head;
        while (temp != NULL)
        {
            printf(" %d ", temp->data); // Print the data of current node
            temp = temp->next;                 // Move to next node
        }
    }
}

int main()
{
    int n, position;

    /*
     * Create a singly linked list of n nodes
     */
    printf("Enter the total number of nodes: ");
    scanf("%d", &n);
    createList(n);

    printf("\nData in the list \n");
    displayList();

    printf("\nEnter the node position you want to delete: ");
    scanf("%d", &position);

    /* Delete middle node from list */
    deleteMiddleNode(position);

    printf("\nData in the list \n");
    displayList();

    return 0;
}

Output


Enter the total number of nodes: 5
Enter the data of node 1: 10
Enter the data of node 2: 20
Enter the data of node 3: 30
Enter the data of node 4: 40
Enter the data of node 5: 50
SINGLY LINKED LIST CREATED SUCCESSFULLY

Data in the list
 10  20  30  40  50
Enter the node position you want to delete: 3
SUCCESSFULLY DELETED NODE FROM MIDDLE OF LIST

Data in the list
 10  20  40  50