How V2EX decides topic order

gistfile1.py

                # Logic to decide how this reply affects ranking of the topic
                now = self.now()
                diff = now - topic.last_touched
                if topic.last_touched < now:
                    if topic.old_topic:
                        if diff > 86400:
                            topic.last_touched = topic.last_touched + int(diff / 8)
                        else:
                            if diff > (3600 * 4):
                                topic.last_touched = topic.last_touched + 3600
                            else:
                                if diff < 3600:
                                    topic.last_touched = now
                                else:
                                    topic.last_touched = topic.last_touched + 600
                    else:
                        if diff > 86400:
                            topic.last_touched = topic.last_touched + int(diff / 4)
                        else:
                            if diff > (3600 * 4):
                                topic.last_touched = topic.last_touched + 3600
                            else:
                                topic.last_touched = now
                else:
                    # Extension: 60s to sticky topic
                    topic.last_touched = topic.last_touched + 60