account.rs

#[derive(Clone, Debug, Default)]
struct Account {
    transactions: Vec<i32>,
    balance: i32,
}

impl Account {
    fn new() -> Self {
        Account {
            balance: 0,
            ..Default::default()
        }
    }

    fn withdrawal(&mut self, request: u32) -> u32 {
        if self.balance <= 0 {
            return 0;
        }

        let balance = self.balance as u32;
        let withdrawal = if balance <= request {
            self.balance
        } else {
            request as i32
        };

        self.transactions.push(-withdrawal);
        self.balance -= withdrawal;

        withdrawal as u32
    }

    fn deposit(&mut self, deposit: i32) {
        self.transactions.push(deposit);
        self.balance += deposit;
    }

    fn balance(&self) -> i32 {
        self.balance
    }
}