def test_get_numbers():
expected = [
35,
20,
15,
25,
47,
40,
62,
55,
65,
95,
102,
117,
150,
182,
127,
219,
299,
277,
309,
576,
]
assert get_numbers(EXAMPLE_CYPHER_PATH) == expected
def test_solver():
example_numbers = get_numbers(EXAMPLE_CYPHER_PATH)
assert solver(example_numbers, 5) == 127
def test_solver():
example_numbers = get_numbers(EXAMPLE_CYPHER_PATH)
with patch("day_9.xmas_cypher_pt2.solver_pt1", return_value=127):
assert solver_pt2(example_numbers) == 62
def sum_min_max(numbers: Iterable[int]) -> int:
"""
calculated the sum of the largest value and smallest value in a given list of numbers
:param numbers: list of numbers
:return: value of min + max
"""
return min(numbers) + max(numbers)
def solver_pt2(cypher: List[int]) -> int:
"""
find the contiguous range of numbers which sum to the value found in part 1, and return min + max
:param cypher: ordered list of numbers
:return: min + max for the contiguous range of numbers summing to the target value
"""
target_sum = solver_pt1(cypher)
n_numbers = len(cypher)
for index in range(n_numbers):
max_window = n_numbers - index
for window_length in range(max_window):
window = get_window(cypher, index, window_length)
if is_sum(window, target_sum):
return sum_min_max(window)
raise NoSolutionError
if __name__ == "__main__":
print(solver_pt2(get_numbers()))
import os
from itertools import combinations
from typing import List
from conf import ROOT_DIR
from day_9.utils import NoSolutionError, get_numbers, get_window, is_sum
CYPHER_PATH = os.path.join(ROOT_DIR, "day_9/xmas_cypher.csv")
def solver(cypher: List[int], preamble_length: int = 25) -> int:
"""
find the first number for which no pair of numbers in the preamble sum to its value
:param cypher: ordered list of numbers
:param preamble_length: length of the preceeding list of numbers
:return: value of the first number which breaks the rule
"""
for index in range(len(cypher)):
window = get_window(cypher, index, preamble_length + 1)
current_number = window[-1]
preamble = set(window[:-1])
if any([is_sum(pair, current_number) for pair in combinations(preamble, 2)]):
pass
else:
return current_number
raise NoSolutionError()
if __name__ == "__main__":
print(solver(get_numbers()))