Process a Timestamped Workspace Credit Ledger

Problem Statement

Design an in-memory credit ledger for corporate workspaces. Workspaces hold integer credit balances and perform various financial transactions over time. Events arrive in non-decreasing order of their timestamp.

Implement the WorkspaceLedger class:

• deposit(workspace_id: str, amount: int, timestamp: int) -> bool: Adds amount credits to workspace_id. If the workspace does not exist, it is created. Returns True.

• spend(workspace_id: str, amount: int, cashback_percent: int, delay: int, timestamp: int) -> bool: Deducts amount credits from workspace_id if its available balance at timestamp is at least amount. If successful, schedules a delayed cashback of floor(amount * cashback_percent / 100) credits to mature at timestamp + delay. Returns True on success, or False if the workspace does not exist or has insufficient funds.

• transfer(from_id: str, to_id: str, amount: int, timestamp: int) -> bool: Transfers amount from from_id to to_id if from_id has sufficient balance at timestamp and both IDs are valid and resolve to different workspaces. Returns True on success, False otherwise.

• merge(source_id: str, target_id: str, timestamp: int) -> bool: Merges source_id into target_id. All current balance, pending cashback rewards, and historical cumulative spend from source_id are permanently transferred to target_id. Future operations targeting source_id automatically resolve to target_id. Returns False if either workspace does not exist or if both IDs resolve to the same workspace; otherwise returns True.

• get_balance(workspace_id: str, timestamp: int) -> int: Returns the available credit balance of workspace_id at timestamp (including all cashbacks that matured on or before timestamp). Returns -1 if the workspace does not exist.

• get_top_spenders(k: int, timestamp: int) -> list[str]: Returns the canonical IDs of the top k workspaces sorted by cumulative amount spent up to and including timestamp in descending order. Break ties by canonical workspace ID in lexicographical ascending order. If fewer than k workspaces have spent credits, return all of them.

Constraints

• Timestamps across all method calls are non-decreasing: 1 <= timestamp <= 10^9.
• 1 <= amount <= 10^6
• 0 <= cashback_percent <= 100
• 1 <= delay <= 10^6
• 1 <= k <= 100
• Up to 50,000 total method calls.
• All workspace IDs consist of alphanumeric characters (length 1 to 32).

Example

ledger = WorkspaceLedger()
ledger.deposit("team-a", 100, 1)          # True, team-a balance = 100
ledger.spend("team-a", 40, 10, 5, 2)     # True, balance = 60; 4 cashback at t=7
ledger.get_balance("team-a", 4)          # 60 (cashback not yet matured)
ledger.get_balance("team-a", 7)          # 64 (cashback matured)
ledger.deposit("team-b", 50, 8)          # True
ledger.merge("team-a", "team-b", 9)      # True, team-b balance = 64 + 50 = 114
ledger.get_balance("team-a", 10)         # 114 (redirected to team-b)
ledger.get_top_spenders(2, 10)           # ["team-b"]