1class Candy:
  2    def __init__(self, mass, uranium):
  3        self.__mass = mass
  4        self.__uranium = uranium
  5        
  6    def get_uranium_quantity(self):
  7        return self.__mass*self.__uranium
  8    
  9    def get_mass(self):
 10        return self.__mass
 11
 12
 13class CandyPouch:
 14    def __init__(self, content=[], uranium_quantity=0):
 15        self.__content = []
 16        self.__uranium_quantity = uranium_quantity
 17        
 18        for mass, uranium in content:
 19            candy = Candy(mass, uranium)
 20            self.__content.append(candy)
 21            self.__uranium_quantity += candy.get_uranium_quantity()
 22        
 23    @property
 24    def critical_uranium_quantity(self):
 25        return self.__uranium_quantity > 20
 26    
 27    @property
 28    def empty(self):
 29        return not self.__content
 30    
 31    @property
 32    def content(self):
 33        return self.__content
 34              
 35    def append(self, candy):
 36        self.__content.append(candy)
 37        self.__uranium_quantity += candy.get_uranium_quantity()
 38        
 39    def remove(self, candy):
 40        self.__content.remove(candy)
 41
 42
 43class Person:
 44    def __init__(self, position):
 45        self._position = position
 46    
 47    def get_closest_person(self, other_people):
 48        person_pos = self.get_position()
 49        distance = []
 50        for other in other_people:
 51            other_pos = other.get_position()
 52            if person_pos == other_pos:
 53                continue
 54            distance.append((((person_pos[0] - other_pos[0]) ** 2 
 55                            + (person_pos[1] - other_pos[1]) ** 2) ** 1/2, other_pos[0], other))
 56            
 57        distance.sort()
 58        return distance[0][2]
 59    
 60    def get_position(self):
 61        return self._position
 62    
 63    def set_position(self, position):
 64        self._position = position
 65
 66
 67class Kid(Person):
 68    def __init__(self, position, initiative):
 69        super().__init__(position)
 70        self.__candy_pouch = CandyPouch()
 71        self.__initiative = initiative
 72        
 73    def get_initiative(self):
 74        return self.__initiative
 75    
 76    def add_candy(self, candy):
 77        self.__candy_pouch.append(candy)
 78    
 79    def is_critical(self):
 80        return self.__candy_pouch.critical_uranium_quantity
 81    
 82
 83class Host(Person):
 84    def __init__(self, position, candies):
 85        super().__init__(position)
 86        self.__candy_pouch = CandyPouch(candies)
 87        
 88    def get_max_mass_candy(self):
 89        def max_mass_candy(content):
 90            return max(content, key=lambda candy: candy.get_mass())
 91        return max_mass_candy
 92        
 93    def remove_candy(self, get_candy):
 94        if not self.__candy_pouch.empty:
 95            candy = get_candy(self.__candy_pouch.content)
 96            self.__candy_pouch.remove(candy)
 97            return candy
 98        return None
 99    
100    
101class FluxCapacitor:
102    def __init__(self, participants):
103        self.__hosts = []
104        self.__kids = []
105        
106        for participant in participants:
107            if isinstance(participant, Host):
108                self.__hosts.append(participant)
109            else:
110                self.__kids.append(participant)
111        
112    def get_victim(self):
113        self.__kids.sort(key=lambda kid: kid.get_initiative(), reverse=True)
114        kid_to_host = {kid: self.__hosts for kid in self.__kids}
115        dead_kids = set()
116        
117        while not dead_kids and any(kid_to_host.values()):
118            for kid, not_visited in kid_to_host.items():
119                if not not_visited:
120                    continue;
121                closest_person = kid.get_closest_person(not_visited)
122                kid.add_candy(closest_person.remove_candy(closest_person.get_max_mass_candy()))
123                kid.set_position(closest_person.get_position())
124                updated_list = list(not_visited)
125                updated_list.remove(closest_person)
126                kid_to_host[kid] = updated_list
127                
128                if kid.is_critical():
129                    dead_kids.add(kid)
130        
131        return dead_kids if dead_kids else None