Question

In C++, change this code to a circular linked list

#include <iostream>
using namespace std;

struct node
{
string data;
node *next;
};

class linked_list
{
private:
node *head,*tail;
public:
linked_list()
{
head = NULL;
tail = NULL;
}

void add_node(string n)
{
node *tmp = new node;
tmp->data = n;
tmp->next = NULL;

if(head == NULL)
{
head = tmp;
tail = tmp;
}
else
{
tail->next = tmp;
tail = tail->next;
}
}

void display()
{
while (tmp != NULL)
{
cout << tmp->data << endl;
tmp = tmp->next;
}
}
};

int main()
{
linked_list a;
a.add_node("One");
a.add_node("Two");
a.display();
return 0;
}

Answer 1

#include <iostream>
using namespace std;

struct node
{
string data;
node *next;
};

class linked_list
{
private:
node *head,*tail;
public:
linked_list()
{
head = NULL;
tail = NULL;
}
  
void add_node(string n)
{
node *tmp = new node;
tmp->data = n;
tmp->next = NULL;
  
if(head == NULL)
{
head = tmp;
tail = tmp;
// making circular by chaning tail pointing to heaa
tail->next=head;
}
else
{
tail->next = tmp;
tail = tail->next;
// making circular by chaning tail pointing to heaa
tail->next=head;
}
}
  
void display()
{
node *tmp=head;
// changed while to do while
do
{
cout << tmp->data << endl;
tmp = tmp->next;
}while (tmp != head);
}

};

int main()
{
linked_list a;
a.add_node("One");
a.add_node("Two");
a.display();
return 0;
}

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