Invoice and Payment Matching (with datetime parsing/comparison)

Invoice & Payment Matching (with datetime parsing/comparison) You are given two sets of records: Invoices: each record has invoice_id, customer_id, amount, currency, created_at (a datetime string). Payments: each record has payment_id, customer_id, amount, currency, paid_at (a datetime string). Implement a matcher that maps invoices to payments. Matching rules Match only within the same customer_id and the same currency. A payment can match at most one invoice (1:1). Match only if payment.amount == invoice.amount. Time constraint: paid_at >= created_at. If multiple payments can match the same invoice, choose the one with the earliest paid_at; if still tied, choose the lexicographically smallest payment_id. Output invoice_id -> null if no match exists. Input / Output Input: two lines of JSON. Line 1: invoices array Line 2: payments array Output: a single JSON object mapping each invoice_id to a payment_id or null. Constraints 1 <= len(invoices), len(payments) <= 2e5 amount is a non-negative integer (in the smallest currency unit, e.g. cents) created_at and paid_at share the same datetime-string format and must be compared correctly Example Input [{"invoice_id":"i1","customer_id":"c1","amount":100,"currency":"USD","created_at":"2020-01-01T00:00:00Z"},{"invoice_id":"i2","customer_id":"c1","amount":100,"currency":"USD","created_at":"2020-01-02T00:00:00Z"}] [{"payment_id":"p1","customer_id":"c1","amount":100,"currency":"USD","paid_at":"2020-01-01T01:00:00Z"},{"payment_id":"p2","customer_id":"c1","amount":100,"currency":"USD","paid_at":"2020-01-03T00:00:00Z"}] Output {"i1":"p1","i2":"p2"}