分数约分

#include <cstdio>
#include <algorithm>
using namespace std;
struct Fraction {//用结构体表示分子和分母
    int up, down;
};
int gcd(int a, int b) {//求出最大公约数
    if (b == 0) {
        return a;
    }
    else {
        return gcd(b, a % b);
    }
}


//表示分数的时候注意规则
//1.down如果为负数，那么令分子表示负数，分母不表示
//2.如果分数为0，则规定分子为0，分母为1
//3.分子分母必须是最简（同时除以最大公约数）
Fraction reduction(Fraction fraction) {
    if (fraction.down < 0) {
        fraction.up = -fraction.up;
        fraction.down = -fraction.down;
    }
    if (fraction.up == 0) {
        fraction.down = 1;
    }
    else {
        int d = gcd(abs(fraction.up), abs(fraction.down));
        fraction.up /= d;   
        fraction.down /= d;   
    }
    return fraction;   
}

int main() {   
    Fraction fraction;//表示分数   
    scanf("%d%d", &fraction.up, &fraction.down);//分子和分母



    Fraction result = reduction(fraction);   
    if (result.down == 1) {   
        printf("%d", result.up);   
    }
    else {   
        printf("%d %d", result.up, result.down);   
    }
    return 0;   
}

分数加法

//加法只是加了一些条件，函数中重新的设置一个分数，进行带入公式
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);
}

#include <cstdio>
#include <algorithm>
using namespace std;

struct Fraction {
    int up, down;
};

int gcd(int a, int b) {
    if (b == 0) {
        return a;
    } else {
        return gcd(b, a % b);
    }
}

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

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);  
}

int main() {  
    Fraction f1, f2;  
    scanf("%d%d%d%d", &f1.up, &f1.down, &f2.up, &f2.down);


    Fraction result = add(f1, f2);  
    if (result.down == 1) {  
        printf("%d", result.up);  
    } else {  
        printf("%d %d", result.up, result.down);  
    }
    return 0;  
}

分数减法

Fraction sub(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);  
}

分数乘法

Fraction mul(Fraction f1, Fraction f2) {  
    Fraction result;  
    result.up = f1.up * f2.up;  
    result.down = f1.down * f2.down;  
    return reduction(result);  
}

分数除法

Fraction div(Fraction f1, Fraction f2) {  
    Fraction result;  
    result.up = f1.up * f2.down;  
    result.down = f1.down * f2.up;  
    return reduction(result);  
}

分数的输出

int main() {  
    Fraction f1, f2;  
    scanf("%d%d%d%d", &f1.up, &f1.down, &f2.up, &f2.down);


    Fraction result = add(f1, f2);  
    if (result.down == 1) {  
        printf("%d", result.up);  
    } else {  
        printf("%d %d", result.up, result.down);  
    }
    return 0;  
}