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82 lines
1.9 KiB
Python
82 lines
1.9 KiB
Python
6 years ago
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#!/usr/bin/env python3
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from pprint import pprint
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with open('input.txt', 'r') as f:
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polymer = f.read()
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print('Polymer length:', len(polymer))
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def reacts(el_1, el_2):
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return el_1 != el_2 and el_1.upper() == el_2.upper()
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def reduce_polymer_naive(polymer):
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"""Faster but not correct solution. Can be used for first reduction of data
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"""
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poly = list(polymer)
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i = 0
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gap = 1
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while i < len(poly):
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if i < 0 or i + gap >= len(poly):
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i += gap
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gap = 1
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continue
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el = poly[i]
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next_el = poly[i + gap]
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if reacts(el, next_el):
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poly[i] = '-'
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poly[i + gap] = '-'
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i -= 1
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gap += 2
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continue
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i += gap
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gap = 1
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return ''.join([el for el in poly if el != '-'])
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def reduce_polymer(polymer):
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polymer = reduce_polymer_naive(polymer)
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modifications = True
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rounds = 0
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while modifications:
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modifications = False
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rounds += 1
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mods = 0
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new_polymer = []
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skip = False
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for i, el in enumerate(polymer[:-1]):
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if skip:
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skip = False
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continue
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next_el = polymer[i + 1]
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if el != next_el and el.upper() == next_el.upper():
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modifications = True
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mods += 1
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skip = True
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continue
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new_polymer.append(el[-1])
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if not skip:
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new_polymer.append(polymer[-1])
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polymer = ''.join(new_polymer)
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return polymer
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alphabet = 'abcdefghijklmnopqrstuvwxyz'
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count_dict = dict()
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for el in alphabet:
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new_poly = ''.join([x for x in polymer if x not in (el, el.upper())])
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count_dict[el] = len(reduce_polymer(new_poly))
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print(f'Processed {el}, len: {count_dict[el]}')
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pprint(count_dict)
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min_idx = min(count_dict, key=count_dict.get)
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print(min_idx, count_dict[min_idx])
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