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python-aoc-2020/day14/part2.py
Sebastian Seedorf 8f140f8e00 Day 14
2020-12-14 09:54:56 +01:00

35 lines
905 B
Python

import re
lines = (x.strip() for x in open("input.txt"))
mem = {}
regex_mask = re.compile(r"mask = (.+)")
regex_mem = re.compile(r"mem\[(.*)] = (.+)")
mask = ""
def combination(res, sum=0):
if len(res) == 0:
yield sum
else:
head, tail = res[0], res[1:]
if head != 'X':
yield from combination(tail, sum=sum*2+int(head))
else:
yield from combination(tail, sum=sum*2)
yield from combination(tail, sum=sum*2+1)
for line in lines:
match = regex_mask.match(line)
if match is not None:
mask = match.group(1)
else:
match = regex_mem.match(line)
addr, dec = list(map(int, match.groups()))
bin = format(addr, '036b')
res = "".join((a if b == '0' else b) for a, b in zip(bin, mask))
for x in combination(res):
mem[x] = dec
print(sum(map(lambda x: mem[x], mem)))