B1034 有理数四则运算 (20分)

// B1034 有理数四则运算 (20分).cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//
learn && wrong：
1、公约数要绝对值
2、化简是if,if_else
3、输出是if_else_else if

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <algorithm>

using namespace std;

typedef long long ll;
ll gcd(ll a, ll b) {
    if (b == 0) {
        return a;
    }
    else {
        return gcd(b, a % b);
    }
}

struct Fraction {
    ll up;
    ll down;
}a,b;

Fraction reduction(Fraction result) {   //化简
    if (result.down < 0) {
        result.up = -result.up;
        result.down = -result.down;
    }
    if (result.up == 0) {
        result.down = 1;
    }
    else {
        ll d = gcd(abs(result.up), abs(result.down));
        result.up = result.up / d;
        result.down = result.down / d;
    }
    return result;
}

Fraction add(Fraction a, Fraction b) {
    Fraction result;
    result.up = a.up * b.down + a.down * b.up;
    result.down = a.down * b.down;
    return reduction(result);
}

Fraction sub(Fraction a, Fraction  b) {
    Fraction result;
    result.up = a.up * b.down - a.down * b.up;
    result.down = a.down * b.down;
    return reduction(result);
}

Fraction plus1(Fraction a, Fraction b) {
    Fraction result;
    result.up = a.up * b.up;
    result.down = a.down * b.down;
    return reduction(result);
}

Fraction division(Fraction a, Fraction b) {
    Fraction result;
    result.up = a.up * b.down;
    result.down = a.down * b.up;
    return reduction(result);
}

void show(Fraction r) {
    //如果是负数，如果是0，如果是假分数
    r = reduction(r);
    if (r.up < 0)printf("(");
    if (r.down == 1) printf("%lld", r.up);
    else if (abs(r.up) > r.down) {
        printf("%lld %lld/%lld", r.up / r.down, abs(r.up) % r.down, r.down);
    }
    else {
        printf("%lld/%lld", r.up, r.down);
    }
    if (r.up < 0) printf(")");
    
}

int main()
{
    scanf("%lld/%lld %lld/%lld", &a.up, &a.down, &b.up, &b.down);
    show(a);
    printf(" + ");
    show(b);
    printf(" = ");
    show(add(a, b));
    printf("\n");
    
    show(a);
    printf(" - ");
    show(b);
    printf(" = ");
    show(sub(a, b));
    printf("\n");

    show(a);
    printf(" * ");
    show(b);
    printf(" = ");
    show(plus1(a, b));
    printf("\n");

    show(a);
    printf(" / ");
    show(b);
    printf(" = ");
    if (b.up == 0) printf("Inf");
    else show(division(a, b));
    printf("\n");
    return 0;
}