One interest rate for every account

Some settings belong to a whole class rather than to one object. Model a bank whose interest rate applies to everyone.

What to build

An Account class with a static interest rate, a static count, and commands that open accounts and apply a year of interest.

Requirements

Keep the rate and the number of accounts as static members, with static member functions to set and read them.
open NAME AMOUNT opens an account. rate R sets the rate in percent. year adds one year of interest to every account.
show prints every account in the order it was opened, with two decimals.
After the last command, print accounts N.

Input

The first line has q. Each of the next q lines is a command.

Output

For each show, one line per account: NAME BALANCE. Then the final accounts N line.

Constraints

1 ≤ q ≤ 100, amounts are from 0 to 1000000, and rates are from 0 to 100. The rate starts at 0.

Example

Input:

5
open Asha 1000
open Bilal 500
rate 10
year
show

Output:

Asha 1100.00
Bilal 550.00
accounts 2

Why it works

Every account reads the same static rate, so changing it once changes it for all of them. A static member function can be called through the class with no account at all.

Examples

Example 1 · Input

5
open Asha 1000
open Bilal 500
rate 10
year
show

Expected output

Asha 1100.00
Bilal 550.00
accounts 2

Example 2 · Input

3
open X 100
year
show

Expected output

X 100.00
accounts 1

Hints

Hint 1

`static double rate;` is shared by all accounts, so one `rate` command changes it for all of them.

Hint 2

A static `int count` that the constructor increases gives the number of accounts opened.

Hint 3

`year` loops over every account and adds `balance * rate / 100` to it.

Solution

Show one correct solution (try it yourself first)

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

class Account {
    static double rate;
    static int count;
    string owner;
    double balance;
public:
    Account(string o, double b) : owner(o), balance(b) {
        count++;
    }
    static void setRate(double r) { rate = r; }
    static int howMany() { return count; }
    void addYear() {
        balance += balance * rate / 100;
    }
    void show() const {
        cout << owner << " " << balance << endl;
    }
};

double Account::rate = 0;
int Account::count = 0;

int main() {
    int q;
    cin >> q;
    vector<Account> accounts;
    cout << fixed << setprecision(2);
    while (q-- > 0) {
        string cmd;
        cin >> cmd;
        if (cmd == "open") {
            string name;
            double amount;
            cin >> name >> amount;
            accounts.push_back(Account(name, amount));
        } else if (cmd == "rate") {
            double r;
            cin >> r;
            Account::setRate(r);
        } else if (cmd == "year") {
            for (Account& a : accounts) a.addYear();
        } else {
            for (const Account& a : accounts) a.show();
        }
    }
    cout << "accounts " << Account::howMany() << endl;
    return 0;
}

Lesson: Static and const members →