Question

C++

1. Please use attached script for your reference to create the node structure and a linked list class, say LinkedList, that has the following basic member methods:
    constructor, destructor//IMPORTANT, display(), add_node().
2. Please implement the following additional member methods:
    Please feel free to change T with any data type you'd like to use for your node stricture's data type.
-- addFirst(T data) // Adds an node with data at the beginning of the list
-- pop() // Removes the first node of the list. Note: Don't forget to delete/re-allocate the dynamic memory
-- contains(T data) // return true or false if a node contains the data exists in the list
-- set(int index, T data) // update the data of the index'th node in the list with data.
-- size() // returns the number of nodes in the list
-- merge(LinkedList linkedlist) //merge this object with linkedlist object. In other words, add all nodes in linkedlist to this object.
Extra Credits:
-- insert(int index, T data) // Adds a node after the node with the 'index' number. Note, you will need to check if the node with the index number exists.
-- remove( int index) // Removes a node after the node with the 'index' number. Note, you will need to check if the node with the index number exists. Note: Don't forget to delete/re-allocate the dynamic memory
3. in main() // write some test code


#include <iostream>
using namespace std;

struct Node
{
    int data;
    Node *link;
};

class linked_list
{
private:
    Node *head,*current;
public:
     //constructor
    linked_list()
    {
        head = NULL;//the head pointer
        current = NULL;//acts as the tail of the list
    }

    //destructor - IMPORTANT
    ~linked_list() {
current = head;
while( current != NULL ) {//the loop stops when both current and head are NULL
    head = head->link;
    delete current;
    current = head;
}

    }

    void add_node(int n)// to add a node at the end of the list
    {
        Node *tmp = new Node;
        tmp->data = n;
        tmp->link = NULL;

        if(head == NULL)
        {
            head = tmp;
            current = tmp;
        }
        else
        {
            current->link = tmp;
            current = current->link;
        }
    }

    void display() // to display all nodes in the list
    {
        Node *tmp;
        tmp = head;
        while (tmp != NULL)
        {
            cout << tmp->data << endl;
            tmp = tmp->link;
        }
    }
};

int main()
{
    linked_list a;
    a.add_node(1);
    a.add_node(2);

a.display();


    return 0;
}

Answer 1

Please follow the below code carefully so as to understand it,

Source code:

#include <iostream>
using namespace std;
struct Node
{
int data;
Node* link;
};
class linked_list
{
private:
Node *head,*current;
public:
//constructor
linked_list()
{
head=NULL;//the head pointer
current=NULL;//acts as the taile pointer
}
//destructor
~linked_list()
{
current=head;
while(current!=NULL)
{
head=head->link;
delete current;
current=head;
}
}
void addFirst(int data)//to add the node at the front of the list
{
Node* tem=new Node;//creating a new node
tem->data=data; //assigning the data of the node to the given data
tem->link=NULL;
if(head==NULL)//if linked list is empty
{
//as only single node will be present both the head and current will point to that node
head=tem;
current=tem;
}
else
{
//as the nodemust be added at the front of the linked list its link must point
//to the present head and we change the present head as the new node
tem->link=head;
head=tem;
}
}
void pop()//removes the first node of the list
{
Node *tem=head;
head=head->link;//as we delete the first node we move the head to its link
delete tem; //this deletes the node to be deleted i.e. the initial head.

}
bool contains(int data)//return true or false if a node contains the data exists in the list
{
Node *tem=head;
while(tem!=NULL)
{
if(tem->data==data)
{
return true;
}
tem=tem->link;
}
return false;

}
Node** head_node()//to return the head node of the currrent linked list object
{
return &head;//returning address of head
}
void set(int index,int data)//update the data of the index'th node in the list with data
{
//here we are assuming index to start with 1.
Node *tem=head;
for(int i=1;i<index;i++)
{
tem=tem->link;//traversing the linked list until we reach the node at the required index
}
tem->data=data;//finally updating the data of the node
}
void merge(linked_list l)//merge this object with the linked list object
{
Node** head1=l.head_node();
while(*head1!=NULL)
{
add_node((*head1)->data);
*head1=(*head1)->link;
}
  
  
  
}
void add_node(int n)//to add a node at the end of the list
{
Node *tmp=new Node;
tmp->data=n;
tmp->link=NULL;
if(head==NULL)
{
head=tmp;
current=tmp;
}
else
{
current->link=tmp;
current=current->link;
}
}
void display()//to display all the nodes in the list
{
Node *tmp;
tmp=head;
while(tmp!=NULL)
{
cout<<tmp->data<<endl;
tmp=tmp->link;
}
}
int size()//returns the number of nodes in the linked list
{
Node* tmp=head;//initializing tmp to point to head
int count=0;//to keep track of number of nodes in the linked list
while(tmp!=NULL)
{
tmp=tmp->link;
count++;
}
return count;
}
void insert(int index,int data)//Adds a node after theh node with the index number
{

//as if linked list contains 4 ellements and
//index is specified as 5 we cannot add after that particular
//place as max value for index is count-1
int cnt=size();

if(index>cnt)
{
cout<<"index does not exist"<<endl;
return;
}
else if(index>=0){
//checking whether index>=0
if(index==0)//to add at the first position of the linked list
{
addFirst(data);//this function creates a new node with the given data and adds it at the front //of the linked list
}
else{
int id=index;
Node* tem=head;
while(index-1!=0)
{
  
tem=tem->link;//traversing to the ith index
index--;
}
  
Node* p=tem->link;
Node* newnode=new Node;

newnode->data=data;
newnode->link=p;//this node points the node which was initially pointed by the node at index
tem->link=newnode;//the index'th node points the current node

if(id==cnt)//as it gets added at the end of the linked list
{   
current=newnode;}
  
return;
}

}
}
void remove(int index)
{
Node* tem=head;
if(index>size()-1)//as there are only n nodes we cannot have a node after nth node to delete
//so we can give a maximum of n-1 to index where n is no of nodes in the linked list;
{
cout<<"index does not exist"<<endl;
return;

}
else if(index>=0)//checking whether index>=0
{
if(index==0)
{
pop();//if the firstnode to be popped we need to give index as 0
//hence we call pop as it ops the first node
}
else
{

for(int i=1;i<index;i++)
{
tem=tem->link;//traversing to the ith index;
}
//to del the index+1th index
if(index==size()-1)
current=tem;//as the indexth node becomes the last node in this case
Node *delnode=tem->link;
tem->link=(tem->link)->link;//to make the indexth node point to
//the node that is pointed by (i+1)th node
delete delnode;//finally deleting the node after the indexth node
}
}
}

};
int main()
{
linked_list a,b;
a.add_node(1);//adding element 1
  
a.add_node(2);//adding element 2
a.add_node(3);//adding element 3
b.add_node(4);//adding elemet 4
b.add_node(5);//adding element 5
a.display();//before merge
a.merge(b);
a.display();//after merge
a.insert(1,10);//inserting node with value 10 after 1rst index node
a.remove(4);//removing node after 4th node
a.display();
cout<<a.size();
cout<<a.contains(11);
cout<<a.contains(10);
//you can try variety of operations...

}

Please be free to ask in case of any queries,Thank you.