Order Book Matching Transactions | Dataford Interview Questions

Tell me about how you would design an order book that matches incoming buy and sell orders and outputs all matched <buy,sell> transaction pairs.

Implement process_orders(orders). Each order is a dictionary with id, side ("BUY" or "SELL"), price, and positive quantity. Process orders in input order using price-time priority: highest-priced buys and lowest-priced sells match first, with FIFO ordering at the same price. Return a list of [buy_id, sell_id, quantity] transactions in matching order. Unfilled quantities remain in the book.

Constraints

0 <= orders.length <= 5 * 10^3
Each order has a unique id
side is either "BUY" or "SELL"
1 <= price <= 10^9
1 <= quantity <= 10^9
Orders must be processed in their input order
A transaction quantity must be positive

Function Signature

def process_orders(orders):

Your question is Order Book Matching Transactions. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Tell me about how you would design an order book that matches incoming buy and sell orders and outputs all matched <buy,sell> transaction pairs.

Constraints

0 <= orders.length <= 5 * 10^3
Each order has a unique id
side is either "BUY" or "SELL"
1 <= price <= 10^9
1 <= quantity <= 10^9
Orders must be processed in their input order
A transaction quantity must be positive

Function Signature

def process_orders(orders):

Your question is Order Book Matching Transactions. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.