Case study: settlement release
Request
The ticketing operations team needs a settlement decision from a small provider ledger.
Data
Every row has id, cents, refund, and status. Later valid duplicates replace earlier ones. Refunds are integer cents.
Deliverable
A net total after validation, latest-row deduplication, settlement filtering, and refunds, followed by the exact review or release recommendation.
A fictional ticketing service receives repeated settlement rows from a provider. Some rows have fractional cents, some identifiers appear more than once, and held transactions must stay out of the payout. The finance team needs a local reconciliation before deciding whether to release the batch.
Build the calculation in five continuing steps. Validate integer amounts, keep the latest valid row for each identifier, select settled rows, subtract refunds, and produce a checked release or review recommendation. Keep the order of those operations explicit. Filtering settled rows before deduplication could revive an older settled row when the latest row is held. A negative net total is the reason for review; a zero total is releasable under this exercise's stated rule.
type LedgerRow={id:string;cents:number;refund:number;status:string};
function solve(value:string):string {const rows=JSON.parse(value) as LedgerRow[];const valid=rows.filter(row=>Number.isInteger(row.cents));const unique=valid;const eligible=unique;const total=eligible.reduce((sum,row)=>sum+row.cents,0);return String(total);}
A complete implementation for the first scenario; trace its input before editing.