Linked_List_basic.cpp

// Linked list operations in C++

#include <stdlib.h>
#include <iostream>

using namespace std;

// Create a node
struct Node {
  int item;
  struct Node* next;
};

void insertAtBeginning(struct Node** ref, int data) {

  // Allocate memory to a node
  struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));

  // insert the item
  new_node->item = data;
  new_node->next = (*ref);

  // Move head to new node
  (*ref) = new_node;
}

// Insert a node after a node
void insertAfter(struct Node* prev_node, int data) {
  if (prev_node == NULL) {
    cout << "the given previous node cannot be NULL";
    return;
  }

  struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));
  new_node->item = data;
  new_node->next = prev_node->next;
  prev_node->next = new_node;
}

void insertAtEnd(struct Node** ref, int data) {
  struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));
  struct Node* last = *ref;

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

  if (*ref == NULL) {
    *ref = new_node;
    return;
  }

  while (last->next != NULL)
    last = last->next;

  last->next = new_node;
  return;
}

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

  if (temp != NULL && temp->item == key) {
    *ref = temp->next;
    free(temp);
    return;
  }
  // Find the key to be deleted
  while (temp != NULL && temp->item != key) {
    prev = temp;
    temp = temp->next;
  }

  // If the key is not present
  if (temp == NULL) return;

  // Remove the node
  prev->next = temp->next;

  free(temp);
}

// Print the linked list
void printList(struct Node* node) {
  while (node != NULL) {
    cout << node->item << " ";
    node = node->next;
  }
}

// Driver program
int main() {
  struct Node* head = NULL;

  insertAtEnd(&head, 1);
  insertAtBeginning(&head, 2);
  insertAtBeginning(&head, 3);
  insertAtEnd(&head, 4);
  insertAfter(head->next, 5);

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

  cout << "\nAfter deleting an element: ";
  deleteNode(&head, 3);
  printList(head);
}