advent-of-code/2020/solutions/9/python/main.py

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2020-12-10 00:05:39 +01:00
from os.path import join, dirname
from typing import List, Optional, Set, Tuple
from itertools import combinations
class XMAS:
def __init__(self, data: str, size: int) -> None:
self.size: int = size
self.position: int = size
self.buffer: List[int] = [
int(x)
for x in data.strip().split('\n')
]
def check_next(self) -> bool:
possible = [
a + b
for a, b in combinations(self.buffer[self.position - self.size: self.position], 2)
]
return self.buffer[self.position] in possible
def find_first_invalid(self) -> int:
l = len(self.buffer)
while self.position < l:
valid = self.check_next()
if not valid:
return self.buffer[self.position]
self.position += 1
raise Exception
def find_slice(self, target: int):
l = len(self.buffer)
for n in range(l):
for m in range(n, l):
slice = self.buffer[n: m]
if sum(slice) == target:
return min(slice) + max(slice)
raise Exception
data = join(dirname(__file__), '../data.txt')
with open(data) as f:
xmas = XMAS(f.read(), 25)
first_invalid = xmas.find_first_invalid()
print(first_invalid)
solution = xmas.find_slice(first_invalid)
print(solution)