Question

2043. 简易银行系统

English Version

题目描述

你的任务是为一个很受欢迎的银行设计一款程序，以自动化执行所有传入的交易（转账，存款和取款）。银行共有 n 个账户，编号从 1 到 n 。每个账号的初始余额存储在一个下标从 0 开始的整数数组 balance 中，其中第 (i + 1) 个账户的初始余额是 balance[i] 。

请你执行所有 有效的 交易。如果满足下面全部条件，则交易 有效 ：

• 指定的账户数量在 1 和 n 之间，且
• 取款或者转账需要的钱的总数 小于或者等于 账户余额。

实现 Bank 类：

• Bank(long[] balance) 使用下标从 0 开始的整数数组 balance 初始化该对象。
• boolean transfer(int account1, int account2, long money) 从编号为 account1 的账户向编号为 account2 的账户转帐 money 美元。如果交易成功，返回 true ，否则，返回 false 。
• boolean deposit(int account, long money) 向编号为 account 的账户存款 money 美元。如果交易成功，返回 true ；否则，返回 false 。
• boolean withdraw(int account, long money) 从编号为 account 的账户取款 money 美元。如果交易成功，返回 true ；否则，返回 false 。

 

示例：

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

解释：
Bank bank = new Bank([10, 100, 20, 50, 30]);
bank.withdraw(3, 10);  // 返回 true ，账户 3 的余额是 $20 ，所以可以取款 $10 。
             // 账户 3 余额为 $20 - $10 = $10 。
bank.transfer(5, 1, 20); // 返回 true ，账户 5 的余额是 $30 ，所以可以转账 $20 。
             // 账户 5 的余额为 $30 - $20 = $10 ，账户 1 的余额为 $10 + $20 = $30 。
bank.deposit(5, 20);   // 返回 true ，可以向账户 5 存款 $20 。
             // 账户 5 的余额为 $10 + $20 = $30 。
bank.transfer(3, 4, 15); // 返回 false ，账户 3 的当前余额是 $10 。
             // 所以无法转账 $15 。
bank.withdraw(10, 50);   // 返回 false ，交易无效，因为账户 10 并不存在。

 

提示：

• n == balance.length
• 1 <= n, account, account1, account2 <= 105
• 0 <= balance[i], money <= 1012
• transfer, deposit, withdraw 三个函数，每个 最多调用 104 次

解法

方法一：模拟

根据题意，我们可以使用一个数组 balance 来模拟银行账户的余额，数组下标从 0 开始，数组的值表示账户的余额。

• 初始化时，我们将 balance 数组赋给成员变量 this.balance，并将 balance 的长度赋给成员变量 this.n。
• transfer 函数中，如果 account1 或 account2 大于 n 或 balance[account1 - 1] 小于 money，则返回 false，否则，将 balance[account1 - 1] 减去 money，将 balance[account2 - 1] 加上 money，并返回 true。
• deposit 函数中，如果 account 大于 n，则返回 false，否则，将 balance[account - 1] 加上 money，并返回 true。
• withdraw 函数中，如果 account 大于 n 或 balance[account - 1] 小于 money，则返回 false，否则，将 balance[account - 1] 减去 money，并返回 true。

以上操作的时间复杂度均为 $O(1)$，空间复杂度为 $O(n)$。其中，$n$ 为 balance 的长度。

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)

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);
 */

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);
 */

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);
 */

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)
 */

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);
 */