单变量多项式（来自文本文件） [英] Single Variable Polynomial (from text file)

问题描述

我想修改下面的代码来从文本文件中读取节点（与硬编码值相比）

I want to modify the below code to read the nodes from a text file (vs. hard-coded values)

此外，从文本文件中读取数据格式：

Furthermore, read data from text file in the format:

P1 = 3 5 1 -1 0 8

P1 = 3 5 1 -1 0 8

P2 = 5 6 2 -1 1 7 0 -4

P2 = 5 6 2 -1 1 7 0 -4

等...

将值P（x）命名并输入剩余数据。有什么建议吗？

Name the values P(x) and input the remaining data. Any advice?

import java.io.DataInputStream;
import java.util.LinkedList;
import java.util.ListIterator;

// A term contains the coefficient and the exponent of x.
class Term {
public Term(int c, int d) {
    coeff = c;
    degree = d;
}

public Term multiply(Term other) {
    return new Term(coeff * other.coeff, degree + other.degree);
}

public void add(int c) {
    coeff += c;
}

public void sub(int c) {
    coeff -= c;
}

public int getCoeff() {
    return coeff;
}

public int getDegree() {
    return degree;
}

private int coeff;
private int degree;
}

// A polynomial made up of terms.
class Polynomial {
// Construct a Polynomial object.
public Polynomial() {
    terms = new LinkedList();
}

public Polynomial add(Polynomial p) {
    Polynomial r = new Polynomial();
    ListIterator iterator = terms.listIterator();
    while (iterator.hasNext()) {
        r.add((Term) iterator.next());
    }
    ListIterator pIterator = p.terms.listIterator();
    while (pIterator.hasNext()) {
        r.add((Term) pIterator.next());
    }
    return r;
}

public Polynomial sub(Polynomial p) {
    Polynomial r = new Polynomial();
    ListIterator iterator = terms.listIterator();
    while (iterator.hasNext()) {
        r.sub((Term) iterator.next());
    }
    ListIterator pIterator = p.terms.listIterator();
    while (pIterator.hasNext()) {
        r.sub((Term) pIterator.next());
    }
    return r;
}

public Polynomial multiply(Polynomial p) {
    Polynomial r = new Polynomial();
    ListIterator iterator = terms.listIterator();
    while (iterator.hasNext()) {
        ListIterator pIterator = p.terms.listIterator();
        Term t1 = (Term) iterator.next();
        while (pIterator.hasNext()) {
            Term t2 = (Term) pIterator.next();
            r.add(t1.multiply(t2));
        }
    }
    return r;
}

// Adds a coefficient and degree as a new Term.

public void addTerm(int c, int d) {
    add(new Term(c, d));
}

// Adds a term

public void add(Term t) {
    int c = t.getCoeff();
    int d = t.getDegree();

    ListIterator iterator = terms.listIterator();
    while (iterator.hasNext()) {
        Term current = (Term) iterator.next();
        if (d == current.getDegree()) {
            if (c == -current.getCoeff())
                iterator.remove();
            else
                current.add(c);
            return;
        } else if (d < current.getDegree()) {
            iterator.previous();
            iterator.add(t);
            return;
        }
    }
    iterator.add(t);
}

public void sub(Term t) {
    int c = t.getCoeff();
    int d = t.getDegree();

    ListIterator iterator = terms.listIterator();
    while (iterator.hasNext()) {
        Term current = (Term) iterator.next();
        if (d == current.getDegree()) {
            if (c == current.getCoeff())
                iterator.remove();
            else
                current.add(-c);
            return;
        } else if (d < current.getDegree()) {
            iterator.previous();
             iterator.add(t);
            current.add(-c);
            return;
        }
    }
    iterator.add(t);

}

// Prints the polynomial.
public void print() {
    ListIterator iterator = terms.listIterator();

    while (iterator.hasNext()) {
        Term current = (Term) iterator.next();
        if (current.getCoeff() != 0) {
            if ((current.getCoeff() < 0) || (!(current.getDegree() != 0))) {
                System.out.print(" ");
            }

            else {
                System.out.print(" + ");
            }
            System.out.print(current.getCoeff());

            if (current.getDegree() > 0) {
                System.out.print("x");
                if (current.getDegree() > 1)
                    System.out.print("^" + current.getDegree());
            }
        }
    }
    System.out.println();
}

@SuppressWarnings("deprecation")
public char getChar() {
    char val = ' ';
    String buffer = "";

    DataInputStream ds = new DataInputStream(System.in);
    try {
        buffer = ds.readLine();
        val = buffer.charAt(0);
    } catch (Exception e) {
    }

    return (val);
}

public char enterNext() {
    System.out.println("Enter next Polynomial? ");
    char ans = this.getChar();
    switch (ans) {
    case 'n':
    case 'N':
        System.out.println("All Done.");
        System.exit(0);
        break;
    case 'y':
    case 'Y':
        System.out.println("Enter next one, please!");
    }
    return ans;
}

private LinkedList terms;
}

// A test program for Polynomial and Term classes.

public class RPC {
private static char ans = 'y';

public static void main(String[] args) {
    Polynomial p = new Polynomial();
    do
     {
    p.addTerm(10, 0);
    p.addTerm(-1, 1);
    p.addTerm(9, 7);
    p.addTerm(5, 10);
    System.out.print("f(x) = ");
    p.print();
    System.out.println();
    Polynomial q = new Polynomial();
     do
    {
    q.addTerm(1, 0);
    q.addTerm(-11, 1);
    q.addTerm(19, 7);
    q.addTerm(15, 10);
    System.out.print("q(x) = ");
    q.print();
     p.enterNext();
    }
     while (!(ans != 'y') | !(ans != 'Y'));
    System.out.println();

    Polynomial a = p.add(q);
    System.out.print("f(x) + q(x) = ");
    a.print();
    Polynomial s = p.sub(p);
    s.print();
    Polynomial m = p.multiply(q);
    System.out.print("f(x) * q(x) = ");
    m.print();
    System.exit(0);

} while (ans != 1000);
}
}

推荐答案

除非您的数据已经是二进制形式，我不会使用 DataInputStream类 。以下示例使用 BufferedReader 撰写 org.jscience.mathematics.function.Polynomial 。

Unless your data is already in binary form, I wouldn't use DataInputStream. The example below uses BufferedReader to compose org.jscience.mathematics.function.Polynomial.

请注意，最高阶系数首先是为了方便应用 Horner的计划 ，如示例所示。

Note that the highest order coefficient is first for convenience in applying Horner's scheme, as shown in this example.

1 2 3 4
4 3 2 1

Coefficient: 1 2 3 4
Polynomial:  [1]x³ + [2]x² + [3]x + [4]
Coefficient: 4 3 2 1
Polynomial:  [4]x³ + [3]x² + [2]x + [1]

代码：

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import org.jscience.mathematics.function.Polynomial;
import org.jscience.mathematics.function.Term;
import org.jscience.mathematics.function.Variable;
import org.jscience.mathematics.number.Integer64;

/** @see http://stackoverflow.com/questions/8276150 */
public class ReadPoly {

    public static void main(String[] args) throws IOException {
        BufferedReader r = new BufferedReader(new FileReader("test.txt"));
        String s;
        while ((s = r.readLine()) != null) {
            System.out.println("Coefficient: " + s);
            Polynomial<Integer64> p = create(s.split(" "));
            System.out.println("Polynomial:  " + p);
        }
    }

    public static Polynomial<Integer64> create(String... a) {
        Variable<Integer64> x = new Variable.Local<Integer64>("x");
        Polynomial<Integer64> px = Polynomial.valueOf(Integer64.ZERO, x);
        for (int i = 0, e = a.length - 1; i < a.length; i++, e--) {
            px = px.plus(Polynomial.valueOf(
                Integer64.valueOf(a[i]), Term.valueOf(x, e)));
        }
        return px;
    }
}

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