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deletion_in_linked_list.cpp
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deletion_in_linked_list.cpp
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#include <bits/stdc++.h>
using namespace std;
class Node
{
public:
int data;
Node *next; // next is a pointer which points to next node.
// constructor-->
Node(int data)
{
this->data = data;
next = NULL;
}
// destructor----->
// to delete first node only
~Node()
{
int value = this->data;
if (this->next != NULL)
{
delete next;
next = NULL;
}
cout << "Memory is free for node with data " << value << endl;
}
};
// insertion at head
void insertAtHead(Node *&head, int d)
{
// new node create
Node *temp = new Node(d);
temp->next = head;
head = temp;
}
// insertion at tail
void insertAtTail(Node *&tail, int d)
{
// new node create
Node *temp = new Node(d);
tail->next = temp;
tail = tail->next;
}
// insert at middle or at given position-->
void insertAtMiddle(Node *&tail, Node *&head, int position, int d)
{
// inserting at start
if (position == 1)
{
insertAtHead(head, d);
return;
}
// middle
Node *temp = head;
int cnt = 1;
while (cnt < position - 1)
{
temp = temp->next;
cnt++;
}
// inserting at last position --> updating tail
if (temp->next == NULL)
{
insertAtTail(tail, d);
return;
}
// creating a new node for d
Node *nodeToInsert = new Node(d);
nodeToInsert->next = temp->next;
temp->next = nodeToInsert;
}
void deleteAtMiddle(Node *&head, int position)
{
// deleting first node
if (position == 1)
{
Node *temp = head; // storing head in temp.
head = head->next;
// memory free of start node-->
temp->next = NULL;
delete temp;
}
else
{
// deleting middle node or last node
Node *curr = head;
Node *prev = NULL;
int cnt = 1;
while (cnt < position)
{
prev = curr;
curr = curr->next;
cnt++;
}
prev->next = curr->next;
curr->next = NULL;
delete curr; // will call the destructor
}
}
// traverse a linked list-------------->
void print(Node *&head)
{
Node *temp = head;
while (temp != NULL)
{
cout << temp->data << " ";
temp = temp->next;
}
cout << endl;
}
int main()
{
Node *node1 = new Node(10); // dynamic object (in heap memory)
// cout << node1->data << endl;
// cout << node1->next << endl;
// head pointed to node1
Node *head = node1; // assignment operator
Node *tail = node1;
// insertAtHead(head, 12);
// print(head);
insertAtTail(tail, 12);
print(head);
// insertAtHead(head, 15);
insertAtTail(tail, 15);
print(head);
int position;
cin >> position;
insertAtMiddle(tail, head, position, 22);
print(head);
cout << "head : " << head->data << " "
<< "tail : " << tail->data << endl;
deleteAtMiddle(head, 1);
print(head);
cout << "head : " << head->data << " "
<< "tail : " << tail->data << endl;
return 0;
}