polynomial.cpp

包括图、二叉树、链表

#include "Polynomial.h"
#include <iostream>
using namespace std;
void Polynomial::mult_term(Polynomial p, Term t)
{
	clear();
	while (!p.empty()) 
	{
		Term pterm;
		p.serve_and_retrieve(pterm);
		Term answer_term(pterm.degree + t.degree,
		t.coefficient * pterm.coefficient);
		append(answer_term);
	}
}
int Polynomial::degree() const
/*
Post: If the Polynomial is identically 0, a result of -1 is returned.
Otherwise the degree of the Polynomial is returned.
*/
{
	if (empty()) return -1;
	Term lead;
	retrieve(lead);
	return lead.degree;
}
void Polynomial::print() const
/*
Post: The Polynomial is printed to cout.
*/
{
	Node *print_node = front;
	bool first_term = true;
	while (print_node != NULL) 
	{
		Term &print_term = print_node->entry;
		if (first_term) 
		{ // In this case, suppress printing an initial '+'.
			first_term = false;
			if (print_term.coefficient < 0) cout << "- ";
		}

		else if (print_term.coefficient < 0) cout << " - ";
		else cout << " + ";
		double r = (print_term.coefficient >= 0)
			? print_term.coefficient : -(print_term.coefficient);
		if (r != 1) cout << r;
		if (print_term.degree > 1) cout << " X^" << print_term.degree;
		if (print_term.degree == 1) cout << " X";
		if (r == 1 && print_term.degree == 0) cout << " 1";
		print_node = print_node->next;
	}
 
	if (first_term)
	cout << "0"; // Print 0 for an empty Polynomial.
	cout << endl;
}
void Polynomial::read()
/*
Post: The Polynomial is read from cin.
*/
{
	clear();
	double coefficient;
	int last_exponent, exponent;
	bool first_term = true;
	cout << "Enter the coefficients and exponents for the polynomial, "
	<< "one pair per line. Exponents must be in descending order."
	<< endl
	<< "Enter a coefficient of 0 or an exponent of 0 to terminate."
	<< endl;
	do
	{
		cout << "coefficient? " << flush;
		cin >> coefficient;
		if (coefficient != 0.0) 
		{
			cout << "exponent? " << flush;
			cin >> exponent;
			if ((!first_term && exponent >= last_exponent) || exponent < 0)
			{
				exponent = 0;
				cout << "Bad exponent: Polynomial ends without its last term."
				<< endl;
			}
			else 
			{
				Term new_term(exponent, coefficient);
				append(new_term);
				first_term = false;
			}
			last_exponent = exponent;
		}
	} while (coefficient != 0.0 && exponent != 0);
}
void Polynomial::equals_sum(Polynomial p, Polynomial q)
/*
Post: The Polynomial object
is reset as the sum of the two parameters.
*/
{
	clear();
	while (!p.empty() || !q.empty())
	{
		Term p_term, q_term;
		if (p.degree() > q.degree()) 
		{
			p.serve_and_retrieve(p_term);
			append(p_term);
		}
		else if (q.degree() > p.degree())
		{
			q.serve_and_retrieve(q_term);
			append(q_term);
		}
		else 
		{
			p.serve_and_retrieve(p_term);
			q.serve_and_retrieve(q_term);
			if (p_term.coefficient + q_term.coefficient != 0) 
			{
				Term answer_term(p_term.degree,
				p_term.coefficient + q_term.coefficient);
				append(answer_term);
			}
		}
	}
}
void Polynomial::equals_difference(Polynomial p, Polynomial q)
{
	clear();
	Term p_term, q_term;
	while (!p.empty() || !q.empty()) 
	{
		if (p.degree() > q.degree())
		{
			p.serve_and_retrieve(p_term);
			append(p_term);
		}
		else if (q.degree() > p.degree())
		{
			q.serve_and_retrieve(q_term);
			q_term.coefficient = -q_term.coefficient;
			append(q_term);
		}
		else 
		{
			p.serve_and_retrieve(p_term);
			q.serve_and_retrieve(q_term);
			if (p_term.coefficient - q_term.coefficient != 0) 
			{
				Term answer_term(p_term.degree,
				p_term.coefficient - q_term.coefficient);
				append(answer_term);
			}
		}
	}
}