有理数。为有理数实现一个不可变数据类型Rational，支持加减乘除操作。
无需测试溢出。
/**
* Description :
* Author : mn@furzoom.com
* Date : Sep 27, 2016 2:19:35 PM
* Copyright (c) 2013-2016, http://furzoom.com All Rights Reserved.
*/
package com.furzoom.lab.algs.ch102;
/**
* ClassName : E10216 <br>
* Function : TODO ADD FUNCTION. <br>
* date : Sep 27, 2016 2:19:35 PM <br>
*
* @version
*/
public class E10216
{
public static void main(String[] args)
{
Rational r = new Rational(2, -6);
System.out.println(r);
Rational r1 = new Rational(1, 5);
Rational r2 = new Rational(-1, 15);
System.out.println(r.plus(r1));
System.out.println(r.plus(r2).plus(r1));
System.out.println(r.minus(r1));
System.out.println(r.times(r1));
System.out.println(r.divides(r1));
System.out.println(r.times(r1).equals(r2));
r = new Rational(0, 2);
System.out.println(r);
System.out.println(r.plus(r1));
r1 = new Rational(1, 3);
r2 = new Rational(2, 3);
System.out.println(r1.plus(r2));
r1 = new Rational(1, 200000000);
r2 = new Rational(1, 300000000);
System.out.println(r1.plus(r2));
r1 = new Rational(1073741789, 20);
r2 = new Rational(1073741789, 30);
System.out.println(r1.plus(r2));
}
}
class Rational
{
private final long num;
private final long den;
public Rational(long numerator, long denominator)
{
if (denominator == 0)
throw new RuntimeException("Denominator is zero");
long g = gcd(numerator, denominator);
if (denominator < 0)
g = -g;
this.num = numerator / g;
this.den = denominator / g;
}
public Rational plus(Rational b)
{
long d = den * b.den;
long n = num * b.den + den * b.num;
return new Rational(n, d);
}
public Rational minus(Rational b)
{
long d = den * b.den;
long n = num * b.den - den * b.num;
return new Rational(n, d);
}
public Rational times(Rational b)
{
return new Rational(num * b.num, den * b.den);
}
public Rational divides(Rational b)
{
return new Rational(num * b.den, den * b.num);
}
public boolean equals(Rational that)
{
if (this == that) return true;
if (that == null) return false;
if (this.getClass() != that.getClass()) return false;
return (num == that.num && den == that.den);
}
private static long gcd(long m, long n)
{
if (m < 0) m = -m;
if (n < 0) n = -n;
if (n == 0) return m;
return gcd(n, m % n);
}
public String toString()
{
if (this.den == 1)
return String.format("%d", this.num);
return String.format("%d/%d", this.num, this.den);
}
}