Build a Progressive Banking System

Progressive Banking System

You are tasked with building the backend logic for a banking system that handles accounts, transfers, and account merging. Each account is identified by a unique integer ID.

Implement the following methods:

1. create_account(account_id): Creates a new account with an initial balance of 0. Returns True if successful, False if the account already exists.
2. deposit(account_id, amount): Increases the balance of the specified account by amount. Returns the new total balance if the account exists, otherwise returns None.
3. request_transfer(from_id, to_id, amount, timestamp): Attempts to reserve amount from from_id. The transfer is only valid if from_id exists and has a balance of at least amount.
   • This reservation expires if not accepted within 1000 time units (i.e., if current_timestamp > reservation_timestamp + 1000).
   • Returns a reservation_id (a positive integer) if successful, otherwise None.
4. accept_transfer(reservation_id, current_timestamp): Completes a valid, non-expired transfer. Deducts the reserved amount from the sender and adds it to the recipient. Returns True if successful, False otherwise.
5. merge_accounts(account_id1, account_id2): Merges account_id2 into account_id1. All funds from account_id2 are moved to account_id1. account_id2 is then deleted and cannot be used again.

Constraints

• amount is always a positive integer.
• account_id is a positive integer.
• reservation_id must be globally unique.
• Ensure merge_accounts handles cases where a target account might have pending transfers.

Examples

bank = BankingSystem()
bank.create_account(1)
bank.deposit(1, 100)
res_id = bank.request_transfer(1, 2, 50, 100) # Returns None, account 2 doesn't exist
bank.create_account(2)
res_id = bank.request_transfer(1, 2, 50, 100) # Returns 1
bank.accept_transfer(1, 500) # Returns True; 1 balance: 50, 2 balance: 50