Solution.rs

struct Bank {
    balance: Vec<i64>,
}

/**
 * `&self` means the method takes an immutable reference.
 * If you need a mutable reference, change it to `&mut self` instead.
 */
impl Bank {
    fn new(balance: Vec<i64>) -> Self {
        Bank { balance }
    }

    fn transfer(&mut self, account1: i32, account2: i32, money: i64) -> bool {
        let (account1, account2, n) = (account1 as usize, account2 as usize, self.balance.len());
        if n < account1 || n < account2 {
            return false;
        }
        if self.balance[account1 - 1] < money {
            return false;
        }
        self.balance[account1 - 1] -= money;
        self.balance[account2 - 1] += money;
        true
    }

    fn deposit(&mut self, account: i32, money: i64) -> bool {
        let (account, n) = (account as usize, self.balance.len());
        if n < account {
            return false;
        }
        self.balance[account - 1] += money;
        true
    }

    fn withdraw(&mut self, account: i32, money: i64) -> bool {
        let (account, n) = (account as usize, self.balance.len());
        if n < account {
            return false;
        }
        if self.balance[account - 1] < money {
            return false;
        }
        self.balance[account - 1] -= money;
        true
    }
}/**
 * Your Bank object will be instantiated and called as such:
 * let obj = Bank::new(balance);
 * let ret_1: bool = obj.transfer(account1, account2, money);
 * let ret_2: bool = obj.deposit(account, money);
 * let ret_3: bool = obj.withdraw(account, money);
 */