数学：分数的加减乘除模板（一）

struct Fraction{     //分数
  int up, down;        //分子，分母
};

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

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <map> 
using namespace std;
int gcd(int a, int b)
{
  if (b == 0) return a;
  else return gcd(b, a % b);
}
struct Fraction
{
  int up, down; 
};
Fraction reduction (Fraction result)
{
  if (result.down < 0)
  {
    result.up = - result.up;
    result.down = - result.down;
  }
  if (result.up == 0) result.down = 1;
  else
  {
    int d = gcd(abs(result.up), abs(result.down));
    result.up /= d;
    result.down /= d;
  }
  return result;
}
Fraction add(Fraction f1, Fraction f2)
{
  Fraction result;
  result.up = f1.up * f2.down + f2.up * f1.down;
  result.down = f1.down * f2.down;
  return reduction(result);
}
void showResult (Fraction r)
{
  r = reduction(r);
  if (r.down == 1) printf("%d", r.up);
  else if (abs(r.up) > r.down)
    printf("%d %d/%d", r.up / r.down, abs(r.up) % r.down, r.down);
  else printf("%d/%d", r.up, r.down);
}
int main()
{
  Fraction f1, f2;
  scanf("%d%d", &f1.up, &f1.down);
  scanf("%d%d", &f2.up, &f2.down);
  Fraction res = add(f1, f2);
  showResult(res);
  return 0;
}

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <map> 
using namespace std;
int gcd(int a, int b)
{
  if (b == 0) return a;
  else return gcd(b, a % b);
}
struct Fraction
{
  int up, down; 
};
Fraction reduction (Fraction result)
{
  if (result.down < 0)
  {
    result.up = - result.up;
    result.down = - result.down;
  }
  if (result.up == 0) result.down = 1;
  else
  {
    int d = gcd(abs(result.up), abs(result.down));
    result.up /= d;
    result.down /= d;
  }
  return result;
}
Fraction minu(Fraction f1, Fraction f2)
{
  Fraction result;
  result.up = f1.up * f2.down - f2.up * f1.down;
  result.down = f1.down * f2.down;
  return reduction(result);
}
void showResult (Fraction r)
{
  r = reduction(r);
  if (r.down == 1) printf("%d", r.up);
  else if (abs(r.up) > r.down)
    printf("%d %d/%d", r.up / r.down, abs(r.up) % r.down, r.down);
  else printf("%d/%d", r.up, r.down);
}
int main()
{
  Fraction f1, f2;
  scanf("%d%d", &f1.up, &f1.down);
  scanf("%d%d", &f2.up, &f2.down);
  Fraction res = minu(f1, f2);
  showResult(res);  
  return 0;
}