Banking System with Historical Snapshots
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CoinbaseFULLTIMEOAProblem statement
Process operations in input order and return one string result for every operation.
Every row starts with an operation name and a unique timestamp. Timestamps are strictly increasing.
["CREATE_ACCOUNT", timestamp, account]: createaccountwith balance0. Returntrue.["DEPOSIT", timestamp, account, amount]: add the positive integeramountand return the account's new decimal balance.["MERGE_ACCOUNTS", timestamp, survivor, absorbed]: add the absorbed account's balance to the survivor, then retire the absorbed account. Returntrue.["SNAPSHOT", timestamp]: capture every active account and balance after all earlier operations. Return the next ID:snapshot0,snapshot1, and so on.["GET_BALANCE_AT_SNAPSHOT", timestamp, account, snapshotId]: return the account's decimal balance in that exact snapshot, ornullif the account did not exist in it.
Snapshots are immutable. A merge never changes an earlier snapshot: before the merge, both account IDs retain their separate saved balances. Later snapshots contain the combined balance only under the survivor's ID, so the absorbed ID returns null there.
Function
processBankingSnapshots(operations: String[][]) → String[]Examples
Example 1
operations = [["CREATE_ACCOUNT","1","alice"],["CREATE_ACCOUNT","2","bob"],["DEPOSIT","3","alice","100"],["DEPOSIT","4","bob","60"],["SNAPSHOT","5"],["MERGE_ACCOUNTS","6","alice","bob"],["SNAPSHOT","7"],["GET_BALANCE_AT_SNAPSHOT","8","alice","snapshot0"],["GET_BALANCE_AT_SNAPSHOT","9","bob","snapshot0"],["GET_BALANCE_AT_SNAPSHOT","10","bob","snapshot1"],["GET_BALANCE_AT_SNAPSHOT","11","alice","snapshot1"]]return = ["true","true","100","60","snapshot0","true","snapshot1","100","60","null","160"]snapshot0 keeps Alice's 100 and Bob's 60. The merge then combines them under Alice. In snapshot1, Bob is absent and Alice has 160.
Example 2
operations = [["CREATE_ACCOUNT","1","main"],["DEPOSIT","2","main","40"],["SNAPSHOT","3"],["CREATE_ACCOUNT","4","aux"],["DEPOSIT","5","aux","25"],["MERGE_ACCOUNTS","6","main","aux"],["DEPOSIT","7","main","10"],["SNAPSHOT","8"],["GET_BALANCE_AT_SNAPSHOT","9","main","snapshot0"],["GET_BALANCE_AT_SNAPSHOT","10","aux","snapshot0"],["GET_BALANCE_AT_SNAPSHOT","11","main","snapshot1"],["GET_BALANCE_AT_SNAPSHOT","12","aux","snapshot1"]]return = ["true","40","snapshot0","true","25","true","75","snapshot1","40","null","75","null"]The auxiliary account was not yet created in snapshot0. After it is merged and another deposit reaches the survivor, snapshot1 contains only main with balance 75.
Example 3
operations = [["CREATE_ACCOUNT","1","cash"],["SNAPSHOT","2"],["DEPOSIT","3","cash","5"],["SNAPSHOT","4"],["DEPOSIT","5","cash","7"],["SNAPSHOT","6"],["GET_BALANCE_AT_SNAPSHOT","7","cash","snapshot0"],["GET_BALANCE_AT_SNAPSHOT","8","cash","snapshot1"],["GET_BALANCE_AT_SNAPSHOT","9","cash","snapshot2"]]return = ["true","snapshot0","5","snapshot1","12","snapshot2","0","5","12"]The three snapshots preserve the account's balances 0, 5, and 12 even though the queries occur after all deposits.
Constraints
1 <= operations.length <= 1000001 <= timestamp <= 1000000000, and operation timestamps are unique and strictly increasing.- Account IDs are non-empty, are created at most once, and contain only letters, digits, and underscores.
- Every
DEPOSITnames an active account and has1 <= amount <= 1000000000. - Every
MERGE_ACCOUNTSnames two distinct active accounts. - Every historical query names an existing snapshot ID.
- Every balance fits in a signed 64-bit integer.
- Every operation has exactly the arguments shown above.