# Linked list delete node from beginning or end
We can delete a node at the beginning or at the end of the linked list.
Firstly check if the list is empty ot not.
Beginning:
- Create a temporary pointer (ptr) & equate it to head to point to the first node.
- Make the head pointer equal to link part of the first node.
- Delete the first node using ptr pointer
End:
- Create a temporary pointer (ptr)
- Check if link part of first node is NULL i.e. Only one node is present. Delete the node and make head equal to NULL.
- If more than one nodes, Traverse to the last node using pointer ptr & keep track of second last node using pointer prev.
- Make the link part of second last node as NULL using prev & delete last node using ptr.
# Source Code - C++
#include <iostream>
using namespace std;
//Creating Node Structure
struct Node{
int data;
Node *link;
};
//creating head pointer and equating to NULL
Node *head=NULL;
//Function to delete node at the beginning
void deleteBeg(){
//if list is empty.
if(head==NULL)
cout<<"LIST IS EMPTY\n";
else
{
Node *ptr=head;
head=head->link;
free(ptr);
}
}
//Function to delete node at the end
void deleteEnd()
{
Node *ptr;
//if list is empty.
if(head==NULL)
cout<<"EMPTY LIST\n";
//if list has only one node.
if(head->link==NULL)
{
ptr=head;
head=NULL;
free(ptr);
}
//Traversing the list.
else
{ Node *prev;
ptr=head;
while(ptr->link!=NULL)
{
prev=ptr;
ptr=ptr->link;
}
prev->link=NULL;
free(ptr);
}
}
//Function to insert at the end of linked list
void insertEnd (int d)
{
Node *ptr = new Node();
ptr->data=d;
ptr->link=NULL;
if(head==NULL)
head=ptr;
else
{
Node *temp = head;
while(temp->link != NULL)
{
temp=temp->link;
}
temp->link=ptr;
}
}
// function to display Linked list
void displayList(){
Node *ptr=head;
if(head==NULL)
cout<<"LIST IS EMPTY\n";
while(ptr!=NULL)
{
cout<<ptr->data<<" ";
ptr=ptr->link;
}
cout<<"\n";
}
//Main Function
int main()
{
insertEnd(1);
insertEnd(2);
insertEnd(3);
insertEnd(4);
insertEnd(5);
displayList();
deleteBeg();
displayList();
deleteEnd();
displayList();
return 0;
}
Time Complexity - At start: O(1), At End O(n)