added code and lab manual for assignment 20 and updated README link

README.md

@@ -16,6 +16,7 @@ In this repository, you'll find codes for Data Structure Lab.
 14. [DSL - Assignment 14 (Selection, Bubble Sorting)](https://git.kska.io/sppu-se-comp-codes/DSL/src/branch/main/assignment-14.py)
 16. [DSL - Assignment 16 (Quick sort)](https://git.kska.io/sppu-se-comp-codes/DSL/src/branch/main/assignment-16.py)
 19. [DSL - Assignment 19 (Pinnacle Club)](https://git.kska.io/sppu-se-comp-codes/DSL/src/branch/main/assignment-19.cpp)
+20. [DSL - Assignment 20 (Cinemax theater)](https://git.kska.io/sppu-se-comp-codes/DSL/src/branch/main/assignment-20.cpp)
 29. [DSL - Assignment 29 (Queue job)](https://git.kska.io/sppu-se-comp-codes/DSL/src/branch/main/assignment-29.cpp)
 30. DSL - Assignment 30 (Priority queue) - _TO BE ADDED_
 31. [DSL - Assignment 31 (Double-ended queue)](https://git.kska.io/sppu-se-comp-codes/DSL/src/branch/main/assignment-31.cpp)
@@ -42,6 +43,7 @@ In this repository, you'll find codes for Data Structure Lab.
 14. [Assignment 14 - Selection, Bubble Sorting](https://git.kska.io/sppu-se-comp-codes/DSL/src/branch/main/lab-manuals/Lab%20Assignment%20B_14.pdf)
 16. [Assignment 16 - Quick sort](https://git.kska.io/sppu-se-comp-codes/DSL/src/branch/main/lab-manuals/Lab%20Assignment%20B_16.pdf)
 19. [Assignment 19 - Pinnacle Club](https://git.kska.io/sppu-se-comp-codes/DSL/src/branch/main/lab-manuals/Lab%20Assignment%20C_19.pdf)
+20. [DSL - Assignment 20 (Cinemax theater)](https://git.kska.io/sppu-se-comp-codes/DSL/src/branch/main/lab-manuals/Lab%20Assignment%20C_20.pdf)
 29. [Assignment 29 - Queue job](https://git.kska.io/sppu-se-comp-codes/DSL/src/branch/main/lab-manuals/Lab%20Assignment%20E_29.pdf)
 30. Assignment 30 - Priority queue - _TO BE ADDED_
 31. [Assignment 31 - Double-ended queue](https://git.kska.io/sppu-se-comp-codes/DSL/src/branch/main/lab-manuals/Lab%20Assignment%20E_31.pdf)

assignment-20.cpp

@@ -0,0 +1,240 @@
+/*
+
+
+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>
+#include<stdlib.h>
+using namespace std;
+class node
+{ public:
+node* next;
+node* prev;
+int seat;
+string id;
+int status;
+};
+class cinemax
+{
+public:
+node* head,* tail ,* temp;
+cinemax()
+{
+head=NULL;
+}
+void create_list();
+void display();
+void book();
+void cancel();
+void avail();
+
+};
+void cinemax::create_list()
+{
+int i=1;
+temp=new node;
+temp->seat=1;
+temp->status=0;
+temp->id="null";
+tail=head=temp;
+for(int i=2;i<=70;i++)
+{
+node *p;
+p= new node;
+p->seat=i;
+p->status=0;
+p->id="null";
+tail->next=p;
+p->prev=tail;
+tail=p;
+tail->next=head;
+head->prev=tail;
+
+}
+}
+void cinemax::display()
+{
+{ int r=1;
+node* temp;
+temp=head;
+int count=0;
+cout<<"\n------------------------------------------------------------------------------------\n";
+cout<<" Screen this way \n";
+cout<<"------------------------------------------------------------------------------------\n";
+while(temp->next!=head)
+{
+if(temp->seat/10==0)
+cout<<"S0"<<temp->seat<<" :";
+else
+cout<<"S"<<temp->seat<<" :";
+
+if(temp->status==0)
+cout<<"|___| ";
+else
+cout<<"|_B_| ";
+count++;
+if(count%7==0)
+{
+cout<<endl;
+r++;
+}
+temp=temp->next;
+}
+cout<<"S"<<temp->seat<<" :";
+if(temp->status==0)
+cout<<"|___| ";
+else
+cout<<"|_B_| ";
+}
+}
+void cinemax::book()
+{ int x;
+string y;
+label:
+cout<<"\n\n\nEnter seat number to be booked\n";
+cin>>x;
+cout<<"Enter your ID number\n";
+cin>>y;
+if(x<1||x>70)
+{
+cout<<"Enter correct seat number to book (1-70)\n";
+goto label;
+}
+node *temp;
+//temp=new node;
+temp=head;
+while(temp->seat!=x)
+{
+temp=temp->next;
+}
+
+if(temp->status==1)
+cout<<"Seat already booked!\n";
+else{
+temp->status=1;
+temp->id=y;
+cout<<"Seat "<<x<<" booked!\n";
+}
+
+}
+void cinemax::cancel()
+{
+int x;
+string y;
+label1:
+cout<<"Enter seat number to cancel booking\n";
+cin>>x;
+cout<<"Enter you ID\n";
+cin>>y;
+if(x<1||x>70)
+{
+cout<<"Enter correct seat number to cancel (1-70)\n";
+goto label1;
+}
+node *temp;
+//temp=new node;
+temp=head;
+while(temp->seat!=x)
+{
+temp=temp->next;
+}
+if(temp->status==0)
+{
+cout<<"Seat not booked yet!!\n";
+}
+else
+{
+if(temp->id==y)
+{
+temp->status=0;
+cout<<"Seat Cancelled!\n";
+}
+
+else
+cout<<"Wrong User ID !!! Seat cannot be cancelled!!!\n";
+}
+}
+void cinemax::avail()
+{
+int r=1;
+node* temp;
+temp=head;
+int count=0;
+cout<<"\n\n\n\n";
+cout<<"\n------------------------------------------------------------------------------------\n";
+cout<<" Screen this way \n";
+cout<<"------------------------------------------------------------------------------------\n";
+while(temp->next!=head)
+{
+{
+if(temp->seat/10==0)
+cout<<"S0"<<temp->seat<<" :";
+else
+cout<<"S"<<temp->seat<<" :";
+if(temp->status==0)
+cout<<"|___| ";
+else if(temp->status==1)
+cout<<" ";
+
+count++;
+if(count%7==0)
+
+{
+
+cout<<endl;
+
+}
+
+}
+temp=temp->next;
+}
+if(temp->status==0)
+{
+cout<<"S"<<temp->seat<<" :";
+
+if(temp->status==0)
+cout<<"|___| ";
+}
+
+}
+int main()
+{ cinemax obj;
+obj.create_list();
+int ch;
+char c='y';
+while(c=='y')
+{ obj.display();
+cout<<"\n*********************************************\n";
+cout<<" CINEMAX MOVIE THEATRE\n";
+cout<<"*********************************************\n";
+cout<<"\nEnter Choice\n1.Current SeatStatus\n2.Book Seat \n3.Available Seat\n4.CancelSeat\n";
+cin>>ch;
+switch(ch)
+{
+case 1:obj.display();
+break;
+case 2: obj.book();
+break;
+case 3:obj.avail();
+break;
+case 4: obj.cancel();
+break;
+default: cout<<"Wrong choice input\n";
+}
+cout<<"\nDo you want to perform any other operation : (y/n)\n";
+cin>>c;
+}
+return 0;
+}
+
+