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  1. #!/bin/env python3
  2.  
  3. import re
  4.  
  5.  
  6. class Molecule(object):
  7.     SPLIT_RE = re.compile(
  8.         '(?P<element>[A-Z][a-z]?)(?P<count>\d*)|'
  9.         '(?P<open>\()|'
  10.         '\)(?P<close>\d+)|'
  11.         '.'
  12.     )
  13.  
  14.     def __init__(self, *, elements):
  15.         self._elements = elements
  16.  
  17.     @classmethod
  18.     def from_string(cls, s):
  19.         molecule, remainder = cls.from_tokens(
  20.             list(cls.SPLIT_RE.finditer(s))
  21.         )
  22.         if remainder is not None:
  23.             raise ValueError
  24.         return molecule
  25.  
  26.     @classmethod
  27.     def from_tokens(cls, tokens):
  28.         molecule = cls(elements=dict())
  29.         while tokens:
  30.             for ind, t in enumerate(tokens):
  31.                 if t.group('element'):
  32.                     molecule += cls.from_token(t)
  33.                 elif t.group('open'):
  34.                     next_, remainder = cls.from_tokens(tokens[ind+1:])
  35.                     next_count = int(remainder[0].group('close'))
  36.                     next_ *= next_count
  37.                     molecule += next_
  38.                     tokens = remainder[1:]
  39.                     break
  40.                 elif t.group('close'):
  41.                     return molecule, tokens[ind:]
  42.                 else:
  43.                     raise ValueError
  44.             else:
  45.                 tokens = False
  46.         return molecule, None
  47.  
  48.     @classmethod
  49.     def from_token(cls, token):
  50.         return cls(
  51.             elements={
  52.                 token.group('element'): int('0'+token.group('count')) or 1
  53.             }
  54.         )
  55.  
  56.     def __mul__(self, other):
  57.         if isinstance(other, int):
  58.             return Molecule(
  59.                 elements={
  60.                     ele: count * other
  61.                     for ele, count in self._elements.items()
  62.                 }
  63.             )
  64.         else:
  65.             raise TypeError
  66.  
  67.     def __add__(self, other):
  68.         if isinstance(other, Molecule):
  69.             elements = self._elements.copy()
  70.             for ele, count in other._elements.items():
  71.                 elements[ele] = elements.get(ele, 0) + count
  72.             return Molecule(
  73.                 elements=elements
  74.             )
  75.         elif other is None:
  76.             return self
  77.         else:
  78.             raise TypeError
  79.  
  80.     def __str__(self):
  81.         return '\n'.join(
  82.             '{k} -> {v}'.format(k=k, v=v)
  83.             for k, v in self._elements.items()
  84.         )
  85.  
  86.  
  87. def main():
  88.     import sys
  89.     for line in sys.stdin:
  90.         m = Molecule.from_string(line)
  91.         print(m)
  92.  
  93.  
  94. if __name__ == '__main__':
  95.     main()
Success #stdin #stdout 0.03s 28352KB
comments (?)
stdin
copy 
C6H12O6
CCl2F2
NaHCO3
C4H8(OH)2
PbCl(NH3)2(COOH)2
stdout
copy 
O -> 6
H -> 12
C -> 6
F -> 2
C -> 1
Cl -> 2
Na -> 1
O -> 3
H -> 1
C -> 1
O -> 2
H -> 10
C -> 4
N -> 2
H -> 8
O -> 4
Pb -> 1
Cl -> 1
C -> 2
https://ideone.com/1IvRCi
language:
Python 3 (python  3.12)
created:
7 years ago
visibility:
public

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