challange-17.py

from read_util import parse_integers

def create_checksum(n, numbers):
    def checksum(i, x):
        return x != n / 2 and any(x + y == n for y in numbers[i:])

    return checksum

def get_preamble(size, input):
    return [next(input) for _ in range(0, size)] 


def find_outlier(buffer, feed):
    n = next(feed)
    if not n: return None
    checksum = create_checksum(n, buffer) 
    
    return (
        n if not any(checksum(i, x) for (i, x) in enumerate(buffer)) 
        else find_outlier(buffer[1:] + [n], feed)
    )

def find_sum_range(current, feed, n):
    range_sum = sum(current)

    if range_sum == n: return current

    next_range = (
        current[1:] if range_sum > n
        else current + [next(feed)]
    )

    return find_sum_range(next_range, feed, n)

# Result
with open('./inputs/input-0I.txt') as f:
    feed = parse_integers(f)
    outlier = find_outlier(get_preamble(25, feed), feed)
    f.seek(0)
    cont_range = find_sum_range([], feed, outlier)

    print(outlier, cont_range)
    print(min(cont_range) + max(cont_range))

# Tests
with open('./inputs/test-0I.txt') as given:

    input = (n for n in [0,9,8])
    assert get_preamble(1, input) == [0], 'Cannot read generator'
    assert get_preamble(2, input) == [9,8], 'Cannot read several lines'

    feed = parse_integers(given)
    outlier = find_outlier(get_preamble(5, feed), feed) 
    given.seek(0)

    cont_range = find_sum_range([], feed, outlier)

    assert outlier == 127
    assert cont_range == [15, 25, 47, 40]
    assert min(cont_range) + max(cont_range) == 62