1from collections import deque
  2
  3
  4class Candy:
  5    """A class that represents radioactive candy."""
  6    def __init__(self, mass, uranium):
  7        self.mass = mass
  8        self.uranium = uranium
  9
 10    def get_mass(self):
 11        """Return the mass of the candy."""
 12        return self.mass
 13
 14    def get_uranium_quantity(self):
 15        """Return the uranium mass in the candy."""
 16        return self.uranium * self.mass
 17
 18
 19class Person:
 20    """A base class that represents a person from Pripyat."""
 21    def __init__(self, position):
 22        self.position = position
 23
 24    def get_position(self):
 25        """Return the position of the person."""
 26        return self.position
 27
 28    def set_position(self, position):
 29        """Set the position of the person."""
 30        self.position = position
 31
 32    def sq_distance_to(self, other):
 33        """Return the square of the distance to another person."""
 34        return ((other.position[0] - self.position[0]) ** 2
 35                + (other.position[1] - self.position[1]) ** 2)
 36
 37
 38class Kid(Person):
 39    """A class that represents a kid from Pripyat."""
 40    def __init__(self, position, initiative):
 41        super().__init__(position)
 42        self.initiative = initiative
 43        self.bag = set()
 44        self._uranium_mass = 0.0
 45
 46    def get_initiative(self):
 47        """Return the initiative of a kid."""
 48        return self.initiative
 49
 50    def add_candy(self, candy):
 51        """Add candy into the bag."""
 52        self._uranium_mass += candy.get_uranium_quantity()
 53        self.bag.add(candy)
 54
 55    def is_critical(self):
 56        """Return whether the mass of the uranium in the bag is critical."""
 57        return self._uranium_mass > 20
 58
 59
 60class Host(Person):
 61    """A class that represents a host from Pripyat."""
 62    def __init__(self, position, candies):
 63        super().__init__(position)
 64        self.bag = [Candy(mass, uranium) for mass, uranium in candies]
 65        self.bag.sort(key=Candy.get_mass)
 66
 67    def remove_candy(self, criterion):
 68        """Remove candy by criterion from a host's bag."""
 69        if not self.bag:
 70            return
 71        candy = criterion(self.bag)
 72        self.bag.remove(candy)
 73        return candy
 74
 75
 76class FluxCapacitor:
 77    """A class that simulates a Halloween night in Pripyat."""
 78    @staticmethod
 79    def _draw_paths(participants):
 80        """Return a dictionary of each kids' path of hosts and the number of hosts."""
 81        kids = {person for person in participants if type(person) is Kid}
 82        hosts = participants - kids
 83
 84        host_paths = {}
 85        for host in hosts:
 86            host_distances = [(host.sq_distance_to(other), other.position[0], other) for other in hosts]
 87            host_distances.sort()
 88            host_paths[host] = deque([host for _, _, host in host_distances])
 89
 90        paths = {}
 91        for kid in kids:
 92            _, _, first_host = min([(kid.sq_distance_to(host), host.position[0], host) for host in hosts])
 93            paths[kid] = host_paths[first_host].copy()
 94        return paths, len(hosts)
 95
 96    def __init__(self, participants):
 97        self._paths, self._path_len = FluxCapacitor._draw_paths(participants)
 98
 99        self._kids_order = list(self._paths.keys())
100        self._kids_order.sort(key=Kid.get_initiative, reverse=True)
101
102    def get_victim(self):
103        """Return a set of the first kids whose candy have reached critical mass or None."""
104        victims = set()
105        has_victims = False
106
107        while self._path_len > 0 and not has_victims:
108            self._path_len -= 1
109            for kid in self._kids_order:
110                host = self._paths[kid].popleft()
111                if not host.bag:
112                    continue
113
114                candy = host.bag.pop()
115                kid.add_candy(candy)
116                if kid.is_critical():
117                    victims.add(kid)
118                    has_victims = True
119
120        return victims if has_victims else None
121
122# the beef has just begun.
123# (Candy := type('Candy', (), {'__init__': lambda _, m, u: (setattr(_, 'm', m), setattr(_, 'u', u * m))[0],'get_mass': lambda _: _.m, 'get_uranium_quantity': lambda _: _.u}), Person := type('Person', (), {'__init__': lambda _, p: setattr(_, 'p', p), 'get_position': lambda _: _.p, 'set_position': lambda _, p: setattr(_, 'p', p), 't': lambda _, o: (o.p[0] - _.p[0]) ** 2 + (o.p[1] - _.p[1]) ** 2}), Kid := type('Kid', (Person,), {'__init__': lambda _, p, i: (Person.__init__(_, p), setattr(_, 'i', i), setattr(_, 'b', set()), setattr(_, 'u', 0.0))[0], 'get_initiative': lambda _: _.i, 'add_candy': lambda _, c: (setattr(_, 'u', _.u + c.u), _.b.add(c))[0], 'is_critical': lambda _: _.u > 20}), Host := type('Host', (Person,), {'__init__': lambda _, p, c: (Person.__init__(_, p), setattr(_, 'b', sorted([Candy(m, u) for m, u in c], key=Candy.get_mass)))[0], 'remove_candy': lambda _, f: (c := f(_.b), _.b.remove(c))[0] if _.b else None}), dp := lambda pp: (kk := {p for p in pp if type(p) is Kid}, hh := pp - kk, hp := {h: deque([h_[2] for h_ in sorted([(h.t(o), o.p[0], o) for o in hh])]) for h in hh}, {k: hp[min([(k.t(h), h.p[0], h) for h in hh])[2]].copy() for k in kk}, len(hh))[-2:], FluxCapacitor := type('FluxCapacitor', (), {'__init__': lambda _, p: (d := dp(p), setattr(_, 'p', d[0]), setattr(_, 'l', d[1]), setattr(_, 'o', sorted(list(_.p.keys()), key=Kid.get_initiative, reverse=True)))[1], 'get_victim': lambda _: (None, v)[v != 1] if (setattr(_, 'l', _.l - 1), v := {k for k in _.o if (k.add_candy(b.pop() if (b := _.p[k].popleft().b) else Candy(0, 0)), k.is_critical())[1]} if _.l >= 0 else 1)[1] else _.get_victim()}))