之前的代码,也是加上virtual修改一下main函数即可

#include<iostream>
#include<iomanip>
#include<string>
#include<vector>
using namespace std;

class Account
{
protected:
    double balance;
public:
    void setBalance(double v) { balance = v; }
    double getBalance() { return balance; }
    Account(double v = 0.0) :balance(v) {}
    virtual bool credit(double val) { balance += val; return true; }
    virtual bool debit(double val) {
        if (balance >= val) return (balance -= val, true);
        else return (cout << "Debit amount exceeded account balance.\n", false);
    }
    bool check() { return balance >= 0; }
    virtual double calculateInterest() { return 0; }
};

class CheckingAccount : public Account
{
private:
    double ff;
public:
    CheckingAccount(double v = 0.0, double f = 0.0) : ff(f) { balance = v; }
    virtual bool credit(double v) {
        if (balance + v - ff >= 0) return (balance += v - ff, true);
        else return (cout << "Operation not permitted.\n", false);
    }
    virtual bool debit(double v) {
        if (balance >= v + ff) return balance -= v + ff, true;
        else return (cout << "Operation not permitted.\n", false);
    }
};

class SavingAccount : public Account
{
private:
    double ra;
public:
    SavingAccount(double v, double r) :ra(r) { balance = v; }
    using Account::credit;
    using Account::debit;
    double calculateInterest() { return balance += balance * ra / 100.0; }
};

vector<Account*> ac;
int main() {
    int n;
    int t;
    double  tmp, inp, outp;
    cin >> n;
    for (int i = 0; i < n; i++)
    {
        cin >> t >> tmp >> inp >> outp;
        if (t) ac.push_back(new CheckingAccount(10000.0, tmp));
        else ac.push_back(new SavingAccount(10000.0, tmp));
        ac[i]->calculateInterest();
        ac[i]->credit(inp);
        ac[i]->debit(outp);
    }
    for (int i = 0; i < n; i++)
    {
        cout << fixed << setprecision(3) << ac[i]->getBalance() << endl;
    }
    return 0;
}