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https://github.com/Crocmagnon/advent-of-code.git
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56 lines
1.6 KiB
Python
56 lines
1.6 KiB
Python
import itertools
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from typing import List
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def main(
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filename: str,
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expected_part_1: int = None,
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expected_part_2: int = None,
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preamble: int = 25,
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):
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print(f"\n+ Running on {filename}")
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with open(filename) as f:
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numbers = list(map(int, f.read().strip().split("\n"))) # type: List[int]
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pointer = preamble
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while pointer < len(numbers) and matches_rule(numbers, pointer, preamble):
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pointer += 1
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counter_part_1 = numbers[pointer]
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range_part_2 = sorted(find_range(numbers, counter_part_1))
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counter_part_2 = range_part_2[0] + range_part_2[-1]
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print(f"1. Found {counter_part_1}")
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if expected_part_1:
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assert expected_part_1 == counter_part_1
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print(f"2. Found {counter_part_2}")
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if expected_part_2:
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assert expected_part_2 == counter_part_2
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def matches_rule(numbers, pointer, preamble):
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range_start = pointer - preamble
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range_end = pointer
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number = numbers[pointer]
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for combination in itertools.combinations(numbers[range_start:range_end], 2):
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if number == sum(combination):
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return True
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return False
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def find_range(numbers, found_in_step_1):
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for i, start in enumerate(numbers):
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total = start
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j = i + 1
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while total < found_in_step_1 and j < len(numbers):
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total += numbers[j]
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j += 1
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if total == found_in_step_1:
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return numbers[i:j]
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raise Exception("Didn't find a valid range")
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if __name__ == "__main__":
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main("inputs/day09-test1", 127, 62, preamble=5)
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main("inputs/day09", 144381670)
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