1class RunewordsCalculator:
 2    def __init__(self, runewords: dict):
 3        self._runewords = runewords
 4        self._runes = []
 5        self._made_runewords = set()
 6    
 7    def add_runes(self, runes):
 8        self._runes.extend(runes)
 9
10    def __iter__(self):
11        return self
12
13    def _can_craft(self, recipe):
14        available = list(self._runes)
15        used_rune_indices = []
16        search_from = 0
17        for rune in recipe:
18            try:
19                rune_idx = available.index(rune, search_from)
20                used_rune_indices.append(rune_idx)
21                search_from = rune_idx + 1
22            except ValueError:
23                return None
24        return used_rune_indices
25
26    def __next__(self):
27        if len(self._made_runewords) == len(self._runewords):
28            raise StopIteration
29        for name, recipe in self._runewords.items():
30            if name not in self._made_runewords:
31                used_rune_indices = self._can_craft(recipe)
32                if used_rune_indices is not None:
33                    self._made_runewords.add(name)
34                    for rune_idx in sorted(used_rune_indices, reverse=True):
35                        self._runes.pop(rune_idx)
36                    return name
37        return None