Banking — Deposit / Withdraw / Transaction / Balance

Requirements Build an append-only account ledger with these operations: deposit(t, amt) adds a positive transaction of amt at timestamp t. withdraw(t, amt) records a withdrawal of amt at timestamp t as a negative transaction. transactions(start, end) returns every recorded entry whose timestamp falls within [start, end]. balance(t) reports the account's cumulative balance through timestamp t. For the initial version, calls arrive in non-decreasing timestamp order. A later…