aoc_day9_2020.py

import operator
from itertools import accumulate, combinations, product

INPUT="""..."""

PREAMBLE = 25

values = [int(n) for n in INPUT.split("\n")]


# Part 1
def is_valid(values, offset):
    return any(sum(x) == values[offset] for x in combinations(values[offset - PREAMBLE:offset], 2))


for i, n in enumerate(values[PREAMBLE:]):
    if not is_valid(values, i + PREAMBLE):
        print(n)
        break


# Part 2
target = 177777905
for (start, start_value), (end, end_value) in product(enumerate(accumulate(values, operator.add)), repeat=2):
    if end_value - start_value == target and end - start >= 2:
        print(min(values[start:end]) + max(values[start:end]))