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DOUBLY_L.CPP
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DOUBLY_L.CPP
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///////////////// DOUBLY LINKED LIST /////////////////
#include<iostream.h>
#include<conio.h>
#include<stdio.h>
// NODE //
template <class T> class node
{
public:
T info;
node<T> *next;
node<T> *prev;
node(T data, node<T> *ptr1 = NULL, node<T> *ptr2 = NULL)
{
info = data;
prev = ptr1;
next = ptr2;
}
};
// LIST CLASS //
template <class T> class list
{
node<T> *head, *tail;
public:
list()
{
head = NULL;
tail = NULL;
}
void addToHead(T);
void addToTail(T);
void delFromHead();
void delFromTail();
void addNodeAtPos(T, T);
int search(T val);
void delNodeFromPos(T);
void reverse();
void concatinate(list<T>,list<T>);
void displayList();
};
/////////////////////////////////////////
template <class T>
void list<T>::addToHead(T val)
{
node<T> *temp;
if(head != NULL)
{
temp = head;
head = new node<T>(val, NULL, head);
temp->prev = head;
if(tail == NULL)
tail = head;
}
else
head = tail = new node<T>(val);
}
///////////////////////////////////////// DONE
template <class T>
void list<T>::addToTail(T val)
{
if(head != NULL)
{
tail->next = new node<T>(val, tail);
tail = tail->next;
}
else
head = tail = new node<T>(val);
}
///////////////////////////////////////// DONE
template <class T>
void list<T>::delFromHead()
{
if(head != NULL)
{
node<T> *temp = head;
cout<<"\nDeleting: "<<temp->info;
if(head == tail)
head = tail = NULL;
else
{
head = head->next;
head->prev = NULL;
}
cout<<"\nDeleted!!";
delete temp;
}
else
cout<<"\nList Underflow!!";
}
///////////////////////////////////////// DONE
template <class T>
void list<T>::delFromTail()
{
if(head != NULL)
{
if(head == tail)
{
node<T> *temp;
cout<<"\nDeleting: "<<tail->info;
head = tail = NULL;
}
else
{
node<T> *temp;
cout<<"\nDeleting: "<<tail->info;
tail = tail->prev;
tail->next = NULL;
}
cout<<"\nDeleted!!";
}
else
cout<<"\nList Underflow!!";
}
///////////////////////////////////////// DONE
template <class T>
void list<T>::addNodeAtPos(T pos, T val)
{
if((head != NULL)||(pos == 1))
{
node<T> *temp;
int c;
if(pos == 1)
{
addToHead(val); // Adds new node to head
return;
}
else
for(temp = head,c = 1; temp!=NULL; temp=temp->next,c++)
if(c+1 == pos)
{
temp->next = new node<T>(val, temp, temp->next);
if(temp != tail)
temp->next->next->prev = temp->next;
return;
}
if(temp == NULL)
cout<<"Invalid position !";
}
else
cout<<"\nList Underflow!!";
}
///////////////////////////////////////// DONE
template <class T>
void list<T>::delNodeFromPos(T pos)
{
if((head != NULL)||(pos == 1))
{
node<T> *temp1, *temp2;
int c;
if(pos == 1)
{
delFromHead();
return;
}
else
for(temp1 = head, temp2 = temp1->next, c = 1; temp2!=NULL; temp1=temp1->next, temp2=temp2->next, c++)
if(c+1 == pos)
{
temp2->next->prev = temp1;
temp1->next = temp2->next;
cout<<"\nDeleted!";
return;
}
if(temp2 == NULL)
cout<<"Invalid position !";
}
else
cout<<"\nList Underflow!!";
}
////////////////////////////////// DONE
template <class T>
int list<T>::search(T val)
{
node<T> *temp;
int i;
for(temp = head, i = 1; temp!=NULL; temp=temp->next, i++)
if(temp->info == val)
return i;
return -1;
}
/////////////////////////////////////////
template <class T>
void list<T>::reverse()
{
if(head != NULL)
{
node<T> *i, *temp, *head2 = tail, *tempSec; //earlier
if(head != tail)
{
test:
for(tempSec = head, temp=head->next; temp->next!=NULL&&tempSec->next != tail; temp=temp->next, tempSec=tempSec->next);
{
temp->next=tempSec;
tempSec->next=NULL;
temp->prev= (head2==temp) ? NULL : i;
tail=tempSec;
i=temp;
if(head!=tail)
goto test;
else
{
tail->prev=i;
head = head2;
}
}
cout<<"\nList reversed.";
}
else
{
cout<<"\nList has only one element.";
}
}
else
cout<<"\nList Underflow!!";
}
/////////////////////////////////////////
template <class T>
void list<T>::displayList()
{
if(head != NULL)
{
cout<<"\nList is:- \n";
cout<<"NULL <-> ";
for(node<T> *temp = head; temp!=NULL; temp=temp->next)
{
cout<<temp->info<<" <-> ";
}
cout<<"NULL";
/* TO DEPICT THE USE OF PREVIOUS & NEXT POINTERS
for(node<T> *temp = head; temp!=NULL; temp=temp->next)
{
cout<<endl<<temp->info<<" |\tPre: "<<temp->prev->info<<",\tNext: "<<temp->next->info;
}
*/
}
else
cout<<"\nList Underflow!!";
}
//-------------------------------------//
/* THE MAIN FUNCTION */
//-------------------------------------//
void main()
{
clrscr();
int choice, x, c;
list<int> ls;
char ch;
here:
clrscr();
cout<<"\nMENU:- \n"
<<"\n1) Add to Head"
<<"\n2) Add to Tail"
<<"\n3) Delete from Head"
<<"\n4) Delete from Tail"
<<"\n5) Add at a loc."
<<"\n6) Delete from a loc."
<<"\n7) Search in list"
<<"\n8) Reverse the list"
<<"\n9) Display\n\n";
cin>>choice;
switch(choice)
{
case 1: clrscr();
cout<<"\nEnter data: ";
cin>>x;
ls.addToHead(x);
break;
case 2: clrscr();
cout<<"\nEnter data: ";
cin>>x;
ls.addToTail(x);
break;
case 3: clrscr();
ls.delFromHead();
break;
case 4: clrscr();
ls.delFromTail();
break;
case 5: clrscr();
cout<<"\nEnter data to add: ";
cin>>x;
cout<<"\nEnter the loc.: ";
cin>>c;
ls.addNodeAtPos(c, x);
break;
case 6: clrscr();
cout<<"\nEnter pos.: ";
cin>>x;
ls.delNodeFromPos(x);
break;
case 7: clrscr();
int pos;
cout<<"\nEnter item to search: ";
cin>>x;
pos = ls.search(x);
if(pos!=-1)
cout<<"\nFound at position: "<<pos;
else
cout<<"\nItem not found!!";
break;
case 8: clrscr();
ls.reverse();
break;
case 9: clrscr();
ls.displayList();
break;
default: "\nInvalid input!!";
}
cout<<"\n\nWanna try again??"
<<"\nHit 'Y', else any other key: ";
cin>>ch;
if(ch == 'y' || ch == 'Y')
goto here;
}