Local Delivery — DoorDash / Instacart
Global batch assignment with min-cost flow, decomposed ETA models, order batching, inventory accuracy, and the three-sided marketplace nobody mentions.
Global batch assignment with min-cost flow, decomposed ETA models, order batching, inventory accuracy, and the three-sided marketplace nobody mentions.
Race-free mutual match detection, precomputed recommendation decks, swipe deduplication with bitmaps, 2B swipes/day of write load, and attention distribution as a design constraint.
Location ingest at a million pings/sec, dispatch as a matching problem, surge from H3 supply-demand ratios, HMM map matching, and a trip state machine that survives dead zones.