Linked_List.cpp

#include <iostream>
using namespace std;

struct Node
{
  int item;
  struct Node* next;
};

struct Node* head = NULL;

void insertAtBeginning(int data)
{
  struct Node* new_node = new Node();

  new_node->item = data;
  new_node->next = head;
  head = new_node;
}

void insertAtEnd(int data)
{
  struct Node* new_node = new Node();
  struct Node* last = head;

  new_node->item = data;
  new_node->next = NULL;

  if (head == NULL)
  {
    head = new_node;
  }

  else
  {
      while (last->next != NULL)
      {
        last = last->next;
        ///i = i+1;
      }

      last->next = new_node;
  }
}

void insertAfter(struct Node* prev_node, int data)
{
  if (prev_node == NULL)
  {
    cout << "\nThe given previous node cannot be NULL..";
  }

  else
  {
    struct Node* new_node = new Node();

    new_node->item = data;
    new_node->next = prev_node->next;
    prev_node->next = new_node;
  }
}

void deleteNode(int key)
{
  struct Node *temp = head, *prev;

  if (temp != NULL && temp->item == key)
  {
    head = temp->next;
    free(temp);
    return;
  }

  while (temp != NULL && temp->item != key)
  {
    prev = temp;
    temp = temp->next;
  }

  if (temp == NULL)
  {
      return;
  }

  prev->next = temp->next;
  free(temp);
}

void printList(struct Node* node)
{
  while (node != NULL)
  {
    cout << node->item << " ";
    node = node->next;
  }
  cout << endl << endl;
}

int main()
{
  insertAtBeginning(5);
  insertAtBeginning(4);
  insertAtBeginning(3);
  insertAtBeginning(2);
  insertAtBeginning(1);

  cout << "Linked list: ";
  printList(head);

  insertAtEnd(10);
  insertAtEnd(11);
  insertAtEnd(12);
  insertAtEnd(13);
  insertAtEnd(14);

  cout << "Linked list: ";
  printList(head);

  insertAfter(head->next->next->next->next, 55);

  cout << "Linked list after inserting 55: ";
  printList(head);

  cout << "\nAfter deleting 3, 11 & 13: ";
  deleteNode(3);
  deleteNode(11);
  deleteNode(13);

  printList(head);

  return 0;
}