Platform Architecture and Logistics System Design Questions

def choose_nearest_driver(drivers, pickup):
    """
    drivers: list of dicts like {'id': 'd1', 'location': (x, y)}
    pickup: tuple (x, y)
    Returns: id of the nearest driver by Manhattan distance, or None if no drivers.
    """
    if not drivers:
        return None

    px, py = pickup
    best_id = None
    best_dist = None

    for driver in drivers:
        dx, dy = driver['location']
        dist = abs(dx - px) + abs(dy - py)

        if best_dist is None or dist < best_dist:
            best_dist = dist
            best_id = driver['id']

    return best_id

import heapq

class DriverScoreQueue:
    def __init__(self):
        # heap stores tuples: (-score, driver_id)
        self._heap = []
        # map driver_id -> current_score; absence means not present
        self._current = {}

    def add(self, driver_id, score):
        """Add new driver or replace existing driver with same id."""
        self._current[driver_id] = score
        heapq.heappush(self._heap, (-score, driver_id))

    def update(self, driver_id, new_score):
        """Update score for existing driver; if not present, behaves like add."""
        # Store new score and push a new heap entry (lazy)
        self._current[driver_id] = new_score
        heapq.heappush(self._heap, (-new_score, driver_id))

    def pop_best(self):
        """Return driver_id with highest current score, removing it from queue.
           Raises KeyError if empty."""
        while self._heap:
            neg_score, driver_id = heapq.heappop(self._heap)
            score = -neg_score
            # If driver_id exists and matches current score, it's valid
            cur = self._current.get(driver_id)
            if cur is None:
                # driver already removed, stale entry
                continue
            if cur == score:
                # valid best; remove from current and return
                del self._current[driver_id]
                return driver_id
            # else stale entry (older score), skip
        raise KeyError("pop from an empty DriverScoreQueue")