建立一个分数类。分数类的数据成员包括分子和分母，操作包括约分、通分、比较、加、减、乘、除、求倒数、显示和输入，并将其集合类和分数类的集合类型或分数类型参数改为引用，并添加复制构造函数。

好的，以下是建立一个分数类的代码：

#include <iostream>
using namespace std;

class Fraction {
private:
    int numerator; // 分子
    int denominator; // 分母

public:
    Fraction(int num = 0, int den = 1) : numerator(num), denominator(den) {}

    // 约分
    void reduce() {
        int gcd = __gcd(numerator, denominator);
        numerator /= gcd;
        denominator /= gcd;
    }

    // 通分
    void commonDenominator(Fraction& other) {
        int lcm = denominator * other.denominator / __gcd(denominator, other.denominator);
        numerator *= lcm / denominator;
        denominator = lcm;
        other.numerator *= lcm / other.denominator;
        other.denominator = lcm;
    }

    // 比较
    bool operator<(const Fraction& other) const {
        return numerator * other.denominator < other.numerator * denominator;
    }

    bool operator==(const Fraction& other) const {
        return numerator * other.denominator == other.numerator * denominator;
    }

    // 加
    Fraction operator+(const Fraction& other) const {
        Fraction res(numerator, denominator);
        res.commonDenominator(const_cast<Fraction&>(other));
        res.numerator += other.numerator;
        res.reduce();
        return res;
    }

    // 减
    Fraction operator-(const Fraction& other) const {
        Fraction res(numerator, denominator);
        res.commonDenominator(const_cast<Fraction&>(other));
        res.numerator -= other.numerator;
        res.reduce();
        return res;
    }

    // 乘
    Fraction operator*(const Fraction& other) const {
        Fraction res(numerator * other.numerator, denominator * other.denominator);
        res.reduce();
        return res;
    }

    // 除
    Fraction operator/(const Fraction& other) const {
        Fraction res(numerator * other.denominator, denominator * other.numerator);
        res.reduce();
        return res;
    }

    // 求倒数
    Fraction reciprocal() const {
        return Fraction(denominator, numerator);
    }

    // 显示
    void display() const {
        cout << numerator << "/" << denominator << endl;
    }

    // 输入
    void input() {
        cin >> numerator >> denominator;
        reduce();
    }
};

// 复制构造函数
Fraction::Fraction(const Fraction& other) {
    numerator = other.numerator;
    denominator = other.denominator;
}

// 集合类
template <typename T>
class Set {
private:
    T* data;
    int size;

public:
    Set(int s = 0) : size(s) {
        data = new T[size];
    }

    Set(const Set& other) : size(other.size) {
        data = new T[size];
        for (int i = 0; i < size; i++) {
            data[i] = other.data[i];
        }
    }

    ~Set() {
        delete[] data;
    }

    Set& operator=(const Set& other) {
        if (this != &other) {
            delete[] data;
            size = other.size;
            data = new T[size];
            for (int i = 0; i < size; i++) {
                data[i] = other.data[i];
            }
        }
        return *this;
    }

    void insert(const T& val) {
        for (int i = 0; i < size; i++) {
            if (data[i] == val) {
                return;
            }
        }
        T* temp = new T[size + 1];
        for (int i = 0; i < size; i++) {
            temp[i] = data[i];
        }
        temp[size++] = val;
        delete[] data;
        data = temp;
    }

    void remove(const T& val) {
        for (int i = 0; i < size; i++) {
            if (data[i] == val) {
                T* temp = new T[size - 1];
                for (int j = 0; j < i; j++) {
                    temp[j] = data[j];
                }
                for (int j = i + 1; j < size; j++) {
                    temp[j - 1] = data[j];
                }
                size--;
                delete[] data;
                data = temp;
                return;
            }
        }
    }

    void display() const {
        for (int i = 0; i < size; i++) {
            cout << data[i] << " ";
        }
        cout << endl;
    }
};

int main() {
    Fraction f1(2, 3), f2(3, 4), f3(4, 5);
    f1.display();
    f2.display();
    f3.display();
    Fraction f4 = f1 + f2;
    f4.display();
    Fraction f5 = f1 - f2;
    f5.display();
    Fraction f6 = f1 * f2;
    f6.display();
    Fraction f7 = f1 / f2;
    f7.display();
    Fraction f8 = f1.reciprocal();
    f8.display();

    Set<Fraction> s1(2);
    s1.insert(f1);
    s1.insert(f2);
    s1.insert(f3);
    s1.display();
    s1.remove(f2);
    s1.display();

    Set<Fraction>& s2 = s1;
    s2.insert(f4);
    s2.display();

    Set<Fraction> s3 = s1;
    s3.display();

    return 0;
}

希望这个代码能够满足你的需求！