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2043. Simple Bank System

Description

You have been tasked with writing a program for a popular bank that will automate all its incoming transactions (transfer, deposit, and withdraw). The bank has n accounts numbered from 1 to n. The initial balance of each account is stored in a 0-indexed integer array balance, with the (i + 1)th account having an initial balance of balance[i].

Execute all the valid transactions. A transaction is valid if:

  • The given account number(s) are between 1 and n, and
  • The amount of money withdrawn or transferred from is less than or equal to the balance of the account.

Implement the Bank class:

  • Bank(long[] balance) Initializes the object with the 0-indexed integer array balance.
  • boolean transfer(int account1, int account2, long money) Transfers money dollars from the account numbered account1 to the account numbered account2. Return true if the transaction was successful, false otherwise.
  • boolean deposit(int account, long money) Deposit money dollars into the account numbered account. Return true if the transaction was successful, false otherwise.
  • boolean withdraw(int account, long money) Withdraw money dollars from the account numbered account. Return true if the transaction was successful, false otherwise.

 

Example 1:

Input
["Bank", "withdraw", "transfer", "deposit", "transfer", "withdraw"]
[[[10, 100, 20, 50, 30]], [3, 10], [5, 1, 20], [5, 20], [3, 4, 15], [10, 50]]
Output
[null, true, true, true, false, false]

Explanation
Bank bank = new Bank([10, 100, 20, 50, 30]);
bank.withdraw(3, 10);    // return true, account 3 has a balance of $20, so it is valid to withdraw $10.
                         // Account 3 has $20 - $10 = $10.
bank.transfer(5, 1, 20); // return true, account 5 has a balance of $30, so it is valid to transfer $20.
                         // Account 5 has $30 - $20 = $10, and account 1 has $10 + $20 = $30.
bank.deposit(5, 20);     // return true, it is valid to deposit $20 to account 5.
                         // Account 5 has $10 + $20 = $30.
bank.transfer(3, 4, 15); // return false, the current balance of account 3 is $10,
                         // so it is invalid to transfer $15 from it.
bank.withdraw(10, 50);   // return false, it is invalid because account 10 does not exist.

 

Constraints:

  • n == balance.length
  • 1 <= n, account, account1, account2 <= 105
  • 0 <= balance[i], money <= 1012
  • At most 104 calls will be made to each function transfer, deposit, withdraw.

Solutions

Solution 1: Simulation

We can use an array \(\textit{balance}\) to store the balance of each account. For each operation, we simply perform the required checks and updates according to the problem statement.

For the \(\textit{transfer}\) operation, we need to check whether the account numbers are valid and whether the balance is sufficient. If the conditions are met, we perform the transfer.

For the \(\textit{deposit}\) operation, we only need to check whether the account number is valid, and then perform the deposit.

For the \(\textit{withdraw}\) operation, we need to check whether the account number is valid and whether the balance is sufficient. If the conditions are met, we perform the withdrawal.

Each operation has a time complexity of \(O(1)\), so the overall time complexity is \(O(q)\), where \(q\) is the number of operations. The space complexity is \(O(1)\).

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class Bank:
    def __init__(self, balance: List[int]):
        self.balance = balance
        self.n = len(balance)

    def transfer(self, account1: int, account2: int, money: int) -> bool:
        if account1 > self.n or account2 > self.n or self.balance[account1 - 1] < money:
            return False
        self.balance[account1 - 1] -= money
        self.balance[account2 - 1] += money
        return True

    def deposit(self, account: int, money: int) -> bool:
        if account > self.n:
            return False
        self.balance[account - 1] += money
        return True

    def withdraw(self, account: int, money: int) -> bool:
        if account > self.n or self.balance[account - 1] < money:
            return False
        self.balance[account - 1] -= money
        return True


# Your Bank object will be instantiated and called as such:
# obj = Bank(balance)
# param_1 = obj.transfer(account1,account2,money)
# param_2 = obj.deposit(account,money)
# param_3 = obj.withdraw(account,money)

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class Bank {
    private long[] balance;
    private int n;

    public Bank(long[] balance) {
        this.balance = balance;
        this.n = balance.length;
    }

    public boolean transfer(int account1, int account2, long money) {
        if (account1 > n || account2 > n || balance[account1 - 1] < money) {
            return false;
        }
        balance[account1 - 1] -= money;
        balance[account2 - 1] += money;
        return true;
    }

    public boolean deposit(int account, long money) {
        if (account > n) {
            return false;
        }
        balance[account - 1] += money;
        return true;
    }

    public boolean withdraw(int account, long money) {
        if (account > n || balance[account - 1] < money) {
            return false;
        }
        balance[account - 1] -= money;
        return true;
    }
}

/**
 * Your Bank object will be instantiated and called as such:
 * Bank obj = new Bank(balance);
 * boolean param_1 = obj.transfer(account1,account2,money);
 * boolean param_2 = obj.deposit(account,money);
 * boolean param_3 = obj.withdraw(account,money);
 */

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class Bank {
public:
    vector<long long> balance;
    int n;

    Bank(vector<long long>& balance) {
        this->balance = balance;
        n = balance.size();
    }

    bool transfer(int account1, int account2, long long money) {
        if (account1 > n || account2 > n || balance[account1 - 1] < money) return false;
        balance[account1 - 1] -= money;
        balance[account2 - 1] += money;
        return true;
    }

    bool deposit(int account, long long money) {
        if (account > n) return false;
        balance[account - 1] += money;
        return true;
    }

    bool withdraw(int account, long long money) {
        if (account > n || balance[account - 1] < money) return false;
        balance[account - 1] -= money;
        return true;
    }
};

/**
 * Your Bank object will be instantiated and called as such:
 * Bank* obj = new Bank(balance);
 * bool param_1 = obj->transfer(account1,account2,money);
 * bool param_2 = obj->deposit(account,money);
 * bool param_3 = obj->withdraw(account,money);
 */

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type Bank struct {
    balance []int64
    n       int
}

func Constructor(balance []int64) Bank {
    return Bank{balance, len(balance)}
}

func (this *Bank) Transfer(account1 int, account2 int, money int64) bool {
    if account1 > this.n || account2 > this.n || this.balance[account1-1] < money {
        return false
    }
    this.balance[account1-1] -= money
    this.balance[account2-1] += money
    return true
}

func (this *Bank) Deposit(account int, money int64) bool {
    if account > this.n {
        return false
    }
    this.balance[account-1] += money
    return true
}

func (this *Bank) Withdraw(account int, money int64) bool {
    if account > this.n || this.balance[account-1] < money {
        return false
    }
    this.balance[account-1] -= money
    return true
}

/**
 * Your Bank object will be instantiated and called as such:
 * obj := Constructor(balance);
 * param_1 := obj.Transfer(account1,account2,money);
 * param_2 := obj.Deposit(account,money);
 * param_3 := obj.Withdraw(account,money);
 */

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class Bank {
    balance: number[];
    constructor(balance: number[]) {
        this.balance = balance;
    }

    transfer(account1: number, account2: number, money: number): boolean {
        if (
            account1 > this.balance.length ||
            account2 > this.balance.length ||
            money > this.balance[account1 - 1]
        )
            return false;
        this.balance[account1 - 1] -= money;
        this.balance[account2 - 1] += money;
        return true;
    }

    deposit(account: number, money: number): boolean {
        if (account > this.balance.length) return false;
        this.balance[account - 1] += money;
        return true;
    }

    withdraw(account: number, money: number): boolean {
        if (account > this.balance.length || money > this.balance[account - 1]) {
            return false;
        }
        this.balance[account - 1] -= money;
        return true;
    }
}

/**
 * Your Bank object will be instantiated and called as such:
 * var obj = new Bank(balance)
 * var param_1 = obj.transfer(account1,account2,money)
 * var param_2 = obj.deposit(account,money)
 * var param_3 = obj.withdraw(account,money)
 */

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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
    }
}

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