Constraints

• 0 <= len(dashers) <= 200000
• Each dasher is a tuple: (driver_id, distance_meters, last_update_ms, available)
• distance_meters and last_update_ms may be None; such dashers must be ignored
• 0 <= stale_after_seconds <= 10^6
• 0 <= jitter_tolerance_m <= 10^6

Examples

Solution

def solution(dashers, current_time_ms, stale_after_seconds, jitter_tolerance_m):
    stale_limit_ms = stale_after_seconds * 1000

    def is_valid(dasher):
        if not isinstance(dasher, (list, tuple)) or len(dasher) != 4:
            return False
        driver_id, distance_meters, last_update_ms, available = dasher
        if not available:
            return False
        if distance_meters is None or last_update_ms is None:
            return False
        if distance_meters < 0:
            return False
        age = current_time_ms - last_update_ms
        if age < 0:
            age = 0
        return age <= stale_limit_ms

    min_distance = None
    for dasher in dashers:
        if is_valid(dasher):
            distance_meters = dasher[1]
            if min_distance is None or distance_meters < min_distance:
                min_distance = distance_meters

    if min_distance is None:
        return -1

    threshold = min_distance + jitter_tolerance_m
    best_id = None
    best_update = None

    for dasher in dashers:
        if not is_valid(dasher):
            continue
        driver_id, distance_meters, last_update_ms, _ = dasher
        if distance_meters <= threshold:
            if best_id is None:
                best_id = driver_id
                best_update = last_update_ms
            elif last_update_ms > best_update:
                best_id = driver_id
                best_update = last_update_ms
            elif last_update_ms == best_update and driver_id < best_id:
                best_id = driver_id
                best_update = last_update_ms

    return best_id if best_id is not None else -1

Time complexity: O(n). Space complexity: O(1).

Hints

1. Be very careful with time units: current_time_ms and last_update_ms are milliseconds, but stale_after_seconds is in seconds.
2. You do not need to sort the whole list. First find the minimum valid distance, then scan again to apply the tie-break rules.