/**********************************************************************
* Fib - setFibNumber
* Inputs: n (int)
* Calculates the n-th Fibonacci number
***********************************************************************/
void Fib::setFibNumber(int n)
{
if (n < 1)
{
cout << "Fibonacci subscript cannot be less than 1\n";
return;
}
/*need to clear fibNumber. setFibNumber() may be called several times on an object and you would have problems if you didn't erase all previous data*/
fibNumber.clear();
fibNumber.insert(1,0); // fibNumber will start as f1. f1 = 1;
fibSubscript = n;
if (n < 3) // can return here if n is 1 or 2.
return;
DLList<int> f2;
f2.insert(1,0); // fibNumber(aka f1) = 1 and f2 = 1. We are rdy to start.
Node<int>* p1;// traversal pointers for DLList objects fibNumber(f1) and f2
Node<int>* p2;
int temp = 0; // used as f1's node value placeholder.
int carry = 0;
for (int i = 0; i < n - 2; i++) //run n - 2 times. f1 and f2 done already
{
//reset pointers to respective beginnings of lists. reset carry to 0
p1 = fibNumber.getFirstNode();
p2 = f2.getFirstNode();
carry = 0;
//Add both lists. fibNumber becomes sum, f2 becomes what fibNumber was
while (p1 != NULL)
{
temp = p1->getData();
p1->setData((p1->getData() + p2->getData() + carry) % 1000000000);
carry = (temp + p2->getData()) / 1000000000;
p2->setData(temp);
p1 = p1->getNext();
p2 = p2->getNext();
}
if (carry == 1) // Account for carry on addition of final nodes.
{
fibNumber.insert(1, fibNumber.getNumItems());
f2.insert(0, f2.getNumItems());
}
}
}
/**********************************************************************
* Fib::display() - Displays the Fibonacci number.
***********************************************************************/
void Fib::display()
{
if (fibSubscript == 0)
{
cout << "Use setFibNumber() to initialize object\n";
return;
}
Node<int>* trav = fibNumber.getFirstNode();
while (trav->getNext() != NULL) // traverse to the end of the list
trav = trav->getNext();
cout << trav->getData();//display most significant node without setw/setfill
trav = trav->getPrevious();
while (trav != NULL) //traverse list in reverse and display w/ setw/setfill
{
cout << setw(9) << setfill('0') << trav->getData();
trav = trav->getPrevious();
}
}
