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Problem · Simulation

Process List of Commands

● MediumStripeNEW GRADOA
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The system simulates a transaction intent management tool to handle the process from initialization to completion and calculate the final balances of merchants' accounts. Transaction states include:

  • PENDING: The transaction is created and awaiting processing.
  • IN_PROGRESS: The transaction is being processed.
  • DONE: The transaction is completed, and the balance is updated.

    • Core Features:

  • START <account_id> <initial_balance> <refund_limit> (optional): Initializes a merchant account with an initial balance and an optional refund limit.
  • NEW <transaction_id> <account_id> <amount>: Creates a transaction intent for the specified account with the given amount in the PENDING state.
  • PROCESS <transaction_id>: Moves a transaction from PENDING to IN_PROGRESS.
  • COMPLETE <transaction_id>: Moves a transaction from IN_PROGRESS to DONE and adds the amount to the merchant's balance.

    • Extended Features:

  • MODIFY <transaction_id> <new_amount>: Updates the amount for a PENDING transaction intent.
  • CANCEL <transaction_id>: Reverts a transaction from IN_PROGRESS to PENDING.
  • RETURN <transaction_id>: Processes a refund for a DONE transaction and deducts the amount from the account's balance.

    • Time-Limited Refunds:

  • Each command includes a <time> marker indicating the timestamp.
  • Merchants can set a refund time limit; transactions can only be refunded within this limit.
    • If no limit is set, refunds are allowed indefinitely.
    • A limit of 0 means no refunds are allowed.

    • Task Objective:

    Process a list of commands to manage transaction intents and output the final balances of all accounts.

    Input Format:

    A time-ordered list of commands.

    Output Format:

    A list of account balances in ascending order by account ID.

    Examples
    01 · Example 1
    commands = ["START account1 0", "NEW txn1 account1 50", "PROCESS txn1", "COMPLETE txn1"]
return = ["account1 50"]

    The commands are processed as follows:

    1. START account1 0: Initializes account1 with a balance of 0.
    2. NEW txn1 account1 50: Creates a new transaction intent txn1 for account1 with an amount of 50 in PENDING state.
    3. PROCESS txn1: Moves txn1 to IN_PROGRESS state.
    4. COMPLETE txn1: Moves txn1 to DONE state and adds the amount to account1's balance, resulting in a final balance of 50.
    The final balance for account1 is 50.

    02 · Example 2
    commands = ["START account1 0", "NEW txn1 account1 50", "PROCESS txn1", "CANCEL txn1", "PROCESS txn1", "COMPLETE txn1", "RETURN txn1"]
return = ["account1 0"]

    The commands are processed as follows:

    1. START account1 0: Initializes account1 with a balance of 0.
    2. NEW txn1 account1 50: Creates a new transaction intent txn1 for account1 with an amount of 50 in PENDING state.
    3. PROCESS txn1: Moves txn1 to IN_PROGRESS state.
    4. CANCEL txn1: Reverts txn1 to PENDING state.
    5. PROCESS txn1: Moves txn1 back to IN_PROGRESS state.
    6. COMPLETE txn1: Moves txn1 to DONE state and adds the amount to account1's balance, resulting in a balance of 50.
    7. RETURN txn1: Processes a refund for txn1 and deducts the amount from account1's balance, resulting in a final balance of 0.
    The final balance for account1 is 0.

    03 · Example 3
    commands = ["1 START account1 0 5", "2 NEW txn1 account1 100", "8 COMPLETE txn1", "11 RETURN txn1", "16 RETURN txn1"]
return = ["account1 100"]

    The commands are processed as follows:

    1. 1 START account1 0 5: Initializes account1 with a balance of 0 and a refund limit of 5.
    2. 2 NEW txn1 account1 100: Creates a new transaction intent txn1 for account1 with an amount of 100 in PENDING state.
    3. 8 COMPLETE txn1: Moves txn1 to DONE state and adds the amount to account1's balance, resulting in a balance of 100.
    4. 11 RETURN txn1: Processes a refund for txn1 within the refund limit and deducts the amount from account1's balance, resulting in a balance of 0.
    5. 16 RETURN txn1: The refund is not processed because it is outside the refund limit, so the balance remains 100.
    The final balance for account1 is 100.

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    public String[] processCommands(String[] commands) {
    // write your code here
}
    commands["START account1 0", "NEW txn1 account1 50", "PROCESS txn1", "COMPLETE txn1"]
    expected["account1 50"]
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