Deadlock-Free Bank Transfer

Process transfers atomically in the given order using a deterministic model. balances maps account names to nonnegative integer balances. Each transfer is [source, destination, amount], with both accounts present and integer amount. A transfer succeeds iff amount > 0, source differs from destination, and source has enough money. Return {'balances': final balances, 'accepted': booleans per transfer, 'lock_orders': sorted distinct [source,destination] for EVERY attempt, including rejected attempts}. Acquire both account locks in lexicographic order and release after each attempt; output the lock plan rather than using real locks. No negative balances or money creation is allowed. Examples (JSON; null means Python None): Input: {"balances": {"a": 10, "b": 0}, "transfers": [["a", "b", 4], ["b", "a", 1]]} Output: {"balances": {"a": 7, "b": 3}, "accepted": [true, true], "lock_orders": [["a", "b"], ["a", "b"]]} Input: {"balances": {"a": 2, "b": 1}, "transfers": [["a", "b", 3]]} Output: {"balances": {"a": 2, "b": 1}, "accepted": [false], "lock_orders": [["a", "b"]]}

def bank_transfer(balances: dict[str, int], transfers: list[list]) -> dict:
    """Apply atomic transfers and report their common lock ordering."""
    pass