2043. Simple Bank System #

Problem #

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The amount of money withdrawn or transferred from is less than or equal to the balance of the account.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 <= 100000
0 <= balance[i], money <= 1000000000000
At most 104 calls will be made to each function transfer, deposit, withdraw.

Problem Summary #

Your task is to design a program for a very popular bank to automatically execute all 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, where the initial balance of the (i + 1)th account is balance[i].

Execute all valid transactions. A transaction is valid if all the following conditions are met:

The specified account number is between 1 and n, and
The total amount of money needed for withdrawal or transfer is less than or equal to the account balance.

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; otherwise, return false.
boolean deposit(int account, long money) Deposits money dollars into the account numbered account. Return true if the transaction was successful; otherwise, return false.
boolean withdraw(int account, long money) Withdraws money dollars from the account numbered account. Return true if the transaction was successful; otherwise, return false.

Solution Approach #

Perform a simple simulation according to the problem statement

Code #

package leetcode

type Bank struct {
	accounts []int64
	n        int
}

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

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

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

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