Linked List SPPU assignment, program to add by append, insert after, before, remove, sort linked list

/*Author:Shubham Patil
Problem statement:

The ticket booking system of Cinemax theater has to be implemented using C++ program. There are 10 rows and 7 seats in each row. Doubly circular linked list has to be maintained to keep track of free seats at rows. Assume some random booking to start with. Use array to store pointers (Head pointer) to each row. On demand

a) The list of available seats is to be displayed

b) The seats are to be booked

c) The booking can be cancelled. 

*/
#include<iostream>
using namespace std;
struct node
{
    int data;
    struct node *next;
};

class sll
{
public:
   node *head;
    sll ()
    {
        head=NULL;
    }
     node *create();
     void display(node *);
     node *insert_beg(node *);
     void insert_after(node *);
     void insert_end(node *);
     node *remove(node *);
     node *createsorted();
     node *merge(node *,node *);
};


node *sll :: create() //
{
    node *n,*last;
    int val ;
    char ch;
    do
    {

     cout<<"\nEnter the number: ";
     cin>>val;
    n=new node;
    n->data=val;
    n->next=NULL;

    if(head==NULL)
     {
    head =n;
    last =n;
     }
    else
    {
    last->next=n;
    last=n;
    }
    cout<<"\n Do u want to insert more nodes?";
    cin>>ch;
}
while(ch=='y');
return(head);
}



node *sll :: insert_beg(node *head) //push
{

    node *temp, *n;
    int val;
    temp=head;
    cout<<"\nEnter the number:";
    cin>>val;
     n=new node;
     n->data=val;
     n->next=NULL;
     if(head==NULL)
     {
     head =n;
     }
    else
    {
        n->next=head;
        head=n;
    }
return (head);
}


void sll :: insert_end(node *head) //append
{
    node *temp,*n;
    int val;
    temp=head;
    cout<<"\nEnter the number:";
    cin>>val;
     n=new node;
     n->data=val;
     n->next=NULL;

    while(temp->next!=NULL)
    {
        temp= temp->next;
    }
    temp->next=n;
}

void sll  :: insert_after(node *head)
{
node *temp,*n;
int val,d;\
temp=head;
cout<<"\nEnter the number:";
cin>>val;
 n=new node;
 n->data=val;
 n->next=NULL;
cout<<"\nEnter the data of node afer which u want to insert a node:";
cin>>d;
while(temp->next!=NULL)
{
 if(temp->data==d)
 break;
else
temp=temp->next;
}
if(temp==NULL)
cout<<"\n Node not found";
else
{
n->next=temp->next;
temp->next=n;
}
}














node *sll::remove(node *head)
{
node *curr,*prev;
int d;
curr=head;
while(curr!=NULL)
{
  if(curr->data<0)
  break;
 else
{
 prev=curr;
 curr=curr->next;
}
}
if(curr==NULL)
cout<<"\nNode not found";
else
{
 if(curr==head)
    head=head->next;
 else
   prev->next=curr->next;
   curr->next=NULL;
   cout<<"\n Node deleted";
}
return(head);
}



node *sll::createsorted()
{
    node *n,*temp,*prev,*head;
     int val;
     char ch;

    temp = NULL;
    head = NULL;
do

{
     cout<<"\nEnter the number:";
     cin>>val;
      n=new node;
     n->data=val;
     n->next=NULL;
    if (head==NULL)
    {
     head=n;
    }
    else
    {
    temp=head;
    prev=NULL;
    while(temp!=NULL)
    {
    if(temp->data<n->data)
     {
    prev=temp;
    temp=temp->next;
    }
    else
    break;
    }
     if(prev==NULL)
     {
     n->next=head;
     head=n;
    }
    else
    {
    n->next=prev->next;
    prev->next=n;
    }
    }
    cout<<"Do you want to insert more nodes?";
    cin>>ch;
    }while(ch=='y');
return(head);
}



node *sll :: merge(node *head1, node *head2)
{
    node *head3;
    head3=NULL;
    if(head==NULL)
     return(head2);
    else if(head2==NULL)
     return(head1);
    if(head->data<=head2->data)
    {
    head3=head1;
    head3->next=merge(head1->next,head2);
    }
    else
    {
    head3=head2;
    head3->next=merge(head1,head2->next);
    }
return(head3);
}


void sll::display(node *temp)
{
    while(temp!=NULL)
    {
        cout<<temp->data<<"->";
        temp=temp->next;
    }
}
int main()
{
 int ch,ch1;
 char c,c1;
 node *head,*head2,*head3,*head1;
 sll s;
 do
 {
 cout<<"\n select a choice:";
cout<<"\n1.create\n2.Display\n3.Insert\n4.Remove\n5.createsored\n";
 cin>>ch;
 switch(ch)
 {
 case 1 : head=s.create();
          break;
 case 2 : s.display(head);
          break;
 case 3 : do
{
      cout<<"\n1.Insert_beg\n2.Insert_end\n3.Insert_after\n";
            cin>>ch1;
            switch(ch1)
            {
             case 1 : head=s.insert_beg(head);
                     break;
             case 2 : s.insert_end(head);
         break;
     case 3 : s.insert_after(head);
                     break;
             }
            cout<<"\ndo u want 2 cont?";
            cin>>c1;
            }while(c1=='y');
            break;
case 4 : head=s.remove(head);
         break;
case 5 : cout<<"\nEnter the list of positive nos:";
         head1=s.createsorted();
s.display(head1);
cout<<"\nEnter the list of negative nos:";
         head2=s.createsorted();
s.display(head2);
        cout<<"\nthe sorted list is :";
        head3=s.merge(head1,head2);
        cout<<"\n";
        s.display(head3);
        break;
}
cout<<"do u want to continue y/n?";
 cin>>c;
}
while(c=='y');
return 0;
}