Write an additional method called push_back(int) that will
1.Write an additional method called push_back(int) that will add an integer to the end of the list. You can modify the provided code. 2.Modify the Node class and LinkedList class so that you can access your parent node (double linked-list).
#include
#include
using namespace std;
typedef int Type;
enum Boolean
{
False = 0, True
};
class Item
{
friend class SLList;
public:
Type getVal()
{
return val;
}
private:
Item(Type value, Item *item = 0)
{
val = value;
next = item;
}
Type val;
Item *next;
};
class SLList
{
public:
class Const_Iterator
{
friend class SLList;
public:
Item *current;
Const_Iterator() :
current(NULL)
{
}
const Item & operator*() const
{
return *this->current;
}
Const_Iterator operator++()
{
current = current->next;
return *this;
}
Const_Iterator operator++(int)
{
Const_Iterator old = *this;
++(*this);
return old;
}
bool operator==(const Const_Iterator & rhs)
{
return current == rhs.current;
}
bool operator!=(const Const_Iterator & rhs)
{
return !(*this == rhs);
}
Item retrieve() const
{
return current->val;
}
Const_Iterator(Item *p) :
current(p)
{
}
};
class Iterator
{
friend class SLList;
public:
Item *current;
Iterator() :
current(NULL)
{
}
const Item & operator*() const
{
return *this->current;
}
Iterator operator++()
{
current = current->next;
return *this;
}
Iterator operator++(int)
{
Iterator old = *this;
++(*this);
return old;
}
bool operator==(const Iterator & rhs) const
{
return current == rhs.current;
}
bool operator!=(const Iterator & rhs)
{
return !(*this == rhs);
}
Item retrieve()
{
return current->val;
}
Iterator(Item *p) :
current(p)
{
}
};
SLList()
{
list = 0;
}
~SLList()
{
remove();
}
void insert(Type someItem);
void append(Type someItem);
int remove(Type someItem);
void remove();
Item *atEnd();
Item *head();
Item *tail();
Boolean isPresent(Type someItem);
Boolean isEmpty();
void display();
private:
Iterator iterator;
Item *list;
Item *atEndItem;
};
Boolean SLList::isEmpty()
{
return list == 0 ? True : False;
}
void SLList::insert(Type val)
{
Item *pt = new Item(val, list); // create new item put it in front of list
assert(pt != 0);
if (list == 0)
{
atEndItem = pt;
}
list = pt; // and point next top the list
}
Item *SLList::atEnd()
{
if (list == 0)
{
return 0;
}
Item *prev, *curr;
prev = curr = list;
while (curr)
{
prev = curr;
curr = curr->next;
}
return prev;
}
Item *SLList::tail()
{
if (list == 0)
{
return 0;
}
Item *prev, *curr;
prev = curr = list;
while (curr)
{
prev = curr;
curr = curr->next;
}
return prev;
}
Item *SLList::head()
{
if (list == 0)
{
cout << "List is empty" << endl;
return 0;
}
else
{
return list;
} // end if
return list;
}
void SLList::append(Type val)
{
Item *pt = new Item(val);
assert(pt != 0);
if (list == 0)
{
list = pt;
}
else
{
atEndItem->next = pt;
}
atEndItem = pt;
}
void SLList::display()
{
cout << "(";
for (Item *pt = list; pt; pt = pt->next)
{
cout << pt->val << " ";
} // end for
cout << ")" << endl;
}
void SLList::remove()
{
Item *pt = list;
while (pt)
{
Item *temp = pt;
pt = pt->next;
delete temp;
} // end while
list = atEndItem = 0;
}
Boolean SLList::isPresent(Type item)
{
Boolean rc = False;
if (list != 0)
{
if (list->val == item || atEndItem->val == item)
{
rc = True;
}
else
{
Item *pt = list->next;
for (; pt != atEndItem; pt = pt->next)
{
if (pt->val == item)
{
rc = True;
} // end if
} // end for
} // end if
} // end if
return rc;
}
int SLList::remove(Type val)
{
Item *pt = list;
int cnt = 0;
while (pt && pt->val == val)
{
Item *tmp = pt->next;
delete pt;
cnt++;
pt = tmp;
} // end while
if ((list = pt) == 0)
{
atEndItem = 0;
return cnt;
} // end if
Item *prv = pt;
pt = pt->next;
while (pt)
{
if (pt->val == val)
{
prv->next = pt->next;
if (atEndItem == pt)
{
atEndItem = prv;
} // end if
delete pt;
++cnt;
pt = prv->next;
}
else
{
prv = pt;
pt = pt->next;
} // end if else
} // end while
return cnt;
}
int main()
{
cout << "Single Linked List Example" << endl;
const int size = 12;
const int odd = 1;
int ix = 0;
SLList il;
SLList::Iterator itr;
if (il.isEmpty() != True || il.isPresent(1024) != False)
{
cerr << "List class internal error (1)" << endl;
}
else
{
cout << "Ok, empty list class" << endl;
} // end ifelse
il.remove(1024);
il.display();
for (ix = 0; ix < size; ++ix)
{
il.append(ix % 2 ? odd : ix);
} // end for
il.display();
if (il.isEmpty() == False)
{
cout << " Head " << il.head()->getVal() << endl;
cout << " Tail " << il.tail()->getVal() << endl;
} // end if
if (il.isPresent(odd) != True)
{
cerr << "List class internal error (2)" << endl;
} // end if
int odd_cnt = il.remove(odd);
cout << odd_cnt << " items of value " << odd << " removed." << endl;
il.display();
if (il.isEmpty() == False)
{
cout << " Head " << il.head()->getVal() << endl;
cout << " Tail " << il.tail()->getVal() << endl;
} // end if
for (ix = 0; ix < odd_cnt; ++ix)
{
il.insert(odd);
} // end for
il.display();
if (il.isEmpty() == False)
{
cout << " Head " << il.head()->getVal() << endl;
cout << " Tail " << il.tail()->getVal() << endl;
} // end if
for (itr = il.head(); itr != il.tail(); itr++)
{
cout << "Itr = " << itr.current->getVal()<< endl;
} // end for
il.remove();
il.display();
if (il.isEmpty() == False)
{
cout << " Head " << il.head()->getVal() << endl;
cout << " Tail " << il.tail()->getVal() << endl;
} // end if
return 0;
}
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