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How do you delete a linked list in C++

Delete the middle node of a Linked List in C++

In this example, we will see a C++ program through which we can delete the middle node of a linked list.

If the length of the linked list is odd then delete (( n+1)/2)th term of the given linked list and if the list is of even length then delete the (n/2+1)th term of the given liked list.

Algorithm:
  • STEP 1: We initiate the two-node pointer name as slow, fast.
  • STEP 2: Each time we increment the slow by one whereas increment the fast pointer by two.
  • STEP 3: Repeat step 2 until the fast pointer goes to the end of the linked list.
  • STEP 4: When fast pointer goes to the end of the list at the same time slow pointer points to the middle of the linked list.
  • STEP 5: Then delete the middle node.
Example

#include <bits/stdc++.h>
using namespace std;
struct node{
int data;
node* next;
};
//Create a new node
struct node* create_node(int x){
struct node* temp= new node;
temp->data=x;
temp->next=NULL;
return temp;
}
//Enter the node into the linked list
void push(node** head,int x){
struct node* store=create_node(x);
if(*head==NULL){
*head =store;
return;
}
struct node* temp=*head;
while(temp->next){
temp=temp->next;
}
temp->next=store;
}
//Delete the middle node from the linked list
void delete_node(node** head){
if((*head)->next==NULL){
*head=NULL;
return;
}
struct node* fast=(*head)->next;
struct node* slow=*head;
while(fast && fast->next && fast->next->next){
slow=slow->next;
fast=fast->next->next;
}
slow->next=slow->next->next;
}
//Print the list
void print(node* head){
struct node* temp=head;
while(temp){
cout<<temp->data<<" ";
temp=temp->next;
}
}
int main()
{
struct node* l=NULL;
push(&l,1);
push(&l,2);
push(&l,3);
push(&l,4);
push(&l,5);
push(&l,6);
push(&l,7);
cout<<"Before the delete operation"<<endl;
print(l);
delete_node(&l);
cout<<"\nAfter the delete operation"<<endl;
print(l);
return 0;
}

Output:
Before the delete operation
1 2 3 4 5 6 7
After the delete operation
1 2 3 5 6 7

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