1034 有理数四则运算 (20分)
本题要求编写程序，计算 2 个有理数的和、差、积、商。
输入格式：
输入在一行中按照 a1/b1 a2/b2 的格式给出两个分数形式的有理数，其中分子和分母全是整型范围内的整数，负号只可能出现在分子前，分母不为 0。
输出格式：
分别在 4 行中按照 有理数1 运算符 有理数2 = 结果 的格式顺序输出 2 个有理数的和、差、积、商。注意输出的每个有理数必须是该有理数的最简形式 k a/b，其中 k 是整数部分，a/b 是最简分数部分；若为负数，则须加括号；若除法分母为 0，则输出 Inf。题目保证正确的输出中没有超过整型范围的整数。
输入样例 1：
2/3 -4/2

输出样例 1：
2/3 + (-2) = (-1 1/3)
2/3 - (-2) = 2 2/3
2/3 * (-2) = (-1 1/3)
2/3 / (-2) = (-1/3)

输入样例 2：
5/3 0/6

输出样例 2：
1 2/3 + 0 = 1 2/3
1 2/3 - 0 = 1 2/3
1 2/3 * 0 = 0
1 2/3 / 0 = Inf

解题思路：进行四则运算时，先求出两个分母的最小公倍数，然后通分进行运算，最后输出即可

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String line = br.readLine();
        String[] lines = line.split(" ");
        String[] x = lines[0].split("/");
        String[] y = lines[1].split("/");
        long a1 = Long.parseLong(x[0]);
        long b1 = Long.parseLong(x[1]);
        long a2 = Long.parseLong(y[0]);
        long b2 = Long.parseLong(y[1]);
        String print1 = getStr(a1, b1);
        String print2 = getStr(a2, b2);
        long c = b1 * b2 / gcd(b1, b2);
        long a3 = a1 * c / b1;
        long a4 = a2 * c / b2;
        long sum = a3 + a4;
        String printSum = getStr(sum, c);
        long d = a3 - a4;
        String printD = getStr(d, c);
        long mulm = b1 * b2;
        long mulz = a1 * a2;
        String printMul = getStr(mulz, mulm);
        String printDiv = "";
        if (a2 != 0) {
            long divm = b1 * a2;
            long divz = a1 * b2;
            printDiv = getStr(divz, divm);
        } else {
            printDiv = "Inf";
        }
        System.out.println(print1 + " + " + print2 + " = " + printSum);
        System.out.println(print1 + " - " + print2 + " = " + printD);
        System.out.println(print1 + " * " + print2 + " = " + printMul);
        System.out.println(print1 + " / " + print2 + " = " + printDiv);
    }

    public static String getStr(long a, long b) {
        String result = "";
        if ((a<0 && b>0) || (a>0 && b<0)) {
            result = result + "(-";
            a = Math.abs(a);
            b = Math.abs(b);
            long gcd = gcd(a, b);
            if (gcd != 1) {
                a = a / gcd;
                b = b / gcd;
            }
            long zs = a / b;
            if (zs != 0) {
                if (a % b != 0) {
                    result += zs + " ";
                    long div = a%b;
                    result += div + "/" + b;
                } else {
                    result += zs;
                }
            }else{
                long div = a%b;
                result += div + "/" + b;
            }
            result += ")";
        } else if (a==0 || b==0) {
            result += 0;
        } else {
            long gcd = gcd(a, b);
            if (gcd != 1) {
                a = a / gcd;
                b = b / gcd;
            }
            long zs = a / b;
            if (zs != 0) {
                if (a % b != 0) {
                    result += zs + " ";
                    long div = a%b;
                    result += div + "/" + b;
                } else {
                    result += zs;
                }
            }else{
                long div = a%b;
                result += div + "/" + b;
            }
        }
        return result;
    }

    public static long gcd(long a, long b) {
        while (a % b != 0) {
            long temp = a % b;
            a = b;
            b = temp;
        }
        return b;
    }
}