rt
支持分数间加减乘除，以及分数和小数的加减乘除，还有输入输出重载。
\(a\) 是分子，\(b\) 是分母，如果 b=0 会 exit(486) 表示错误。
分数的符号以分子的正负号表示。
可以用这个去水掉烂题 NOIP2020T1（记得开__int128）。
code
#include <bits/stdc++.h>
//#define int int64_t
//#define int __int128
//#define MOD (1000000007)
//#define eps (1e-6)
#define endl '\n'
#define debug_endl cout<<endl;
#define debug cout<<"debug"<<endl;
using namespace std;
struct Rnumber{int a,b;inline Rnumber(){a=0,b=1;}inline Rnumber(int _a,int _b){a=_a,b=_b;}inline void limit(int &_a,int &_b){//内置化简/统一分数格式if(_b<0) _a=-_a,_b=-_b; //正负号统一在分子上if(b==0) exit(486); //b=0不是个实数，返回错误int flag=(_a<0?-1:1); //以免gcd输入负数int t=__gcd(_a*flag,_b); //分数化简_a/=t,_b/=t;_a*=flag;}//重载运算符inline Rnumber operator+(const Rnumber& other){//分数+分数int _a=a*other.b+other.a*b,_b=other.b*b;limit(_a,_b);return Rnumber(_a,_b);}inline Rnumber operator-(const Rnumber& other){//分数-分数int _a=a*other.b-other.a*b,_b=other.b*b;limit(_a,_b);return Rnumber(_a,_b);}inline Rnumber operator*(const Rnumber& other){//分数*分数int _a=a*other.a,_b=other.b*b;limit(_a,_b);return Rnumber(_a,_b);}inline Rnumber operator/(const Rnumber& other){//分数/分数int _a=a*other.b,_b=other.a*b;limit(_a,_b);return Rnumber(_a,_b);}inline Rnumber operator+(const int& other){//分数+整数int _a=a+other*b,_b=b;limit(_a,_b);return Rnumber(_a,_b);}inline Rnumber operator-(const int& other){//分数-整数int _a=a-other*b,_b=b;limit(_a,_b);return Rnumber(_a,_b);}inline Rnumber operator*(const int& other){//分数*整数int _a=a*other,_b=b;limit(_a,_b);return Rnumber(_a,_b);}inline Rnumber operator/(const int& other){//分数/整数int _a=a,_b=b*other;limit(_a,_b);return Rnumber(_a,_b);}//以下对应上面基本二元运算符的一元形式inline Rnumber operator+=(const Rnumber& other){*this=*this+other;return *this;}inline Rnumber operator-=(const Rnumber& other){*this=*this-other;return *this;}inline Rnumber operator*=(const Rnumber& other){*this=*this*other;return *this;}inline Rnumber operator/=(const Rnumber& other){*this=*this/other;return *this;}inline Rnumber operator+=(const int& other){*this=*this+other;return *this;}inline Rnumber operator-=(const int& other){*this=*this-other;return *this;}inline Rnumber operator*=(const int& other){*this=*this*other;return *this;}inline Rnumber operator/=(const int& other){*this=*this/other;return *this;}friend std::istream& operator>>(std::istream& is, Rnumber& f) {//重载输入is>>f.a>>f.b;return is;}friend std::ostream& operator<<(std::ostream& os, const Rnumber& f) {//重载输出os<<f.a<<' '<<f.b;return os;}
};
signed main(){//freopen(".in","r",stdin);//freopen(".out","w",stdout);Rnumber a,b;int c;cout<<"输入分数a:";cin>>a;cout<<"输入分数b:";cin>>b;cout<<"输入整数c:";cin>>c;cout<<"你输入的分数为:"<<a<<endl<<b<<endl;cout<<"a+b:"<<a+b<<endl;cout<<"a-b:"<<a-b<<endl;cout<<"a*b:"<<a*b<<endl;cout<<"a/b:"<<a/b<<endl;cout<<"a+c:"<<a+c<<endl;cout<<"a-c:"<<a-c<<endl;cout<<"a*c:"<<a*c<<endl;cout<<"a/c:"<<a/c<<endl;return 0;
}