91 lines
2.9 KiB
Python
91 lines
2.9 KiB
Python
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# SPDX-License-Identifier: MIT
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# Copyright (c) 2023 Akumatic
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#
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# https://adventofcode.com/2023/day/3
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def read_file(filename: str = "input.txt") -> list:
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with open(f"{__file__.rstrip('code.py')}{filename}", "r") as f:
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return f.read().strip().split("\n")
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def check_surrounding_fields(vals: list, x: int, y: int) -> bool:
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return any(
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vals[y + j][x + i] != "." and not vals[y + j][x + i].isdigit()
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for i in range(-1, 2) for j in range(-1, 2)
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if 0 <= x + i < len(vals[0]) and 0 <= y + j < len(vals)
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)
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def sum_part_numbers(vals: list) -> int:
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num_sum = 0
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for y in range(len(vals)):
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valid = False
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num = 0
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for x in range(len(vals[0])):
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if not vals[y][x].isdigit():
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if valid:
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num_sum += num
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valid = False
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num = 0
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continue
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num = num * 10 + int(vals[y][x])
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if not valid:
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valid = check_surrounding_fields(vals, x, y)
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if valid:
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num_sum += num
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return num_sum
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def find_possible_gears(vals: list) -> list:
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positions = list()
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for y in range(len(vals)):
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positions.extend([(x, y) for x, char in enumerate(vals[y]) if vals[y][x] == "*"])
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return positions
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def check_left_of_symbol(vals: list, x, y) -> int:
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if not 0 <= y < len(vals):
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return -1
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i, num = 1, 0
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check = False
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while (x - i) >= 0 and vals[y][x - i].isdigit():
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check = True
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num += int(vals[y][x - i]) * 10**(i - 1)
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i += 1
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return num if check else -1
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def check_right_of_symbol(vals:list, x, y) -> int:
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if not 0 <= y < len(vals):
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return -1
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i, num = 1, 0
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check = False
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while (x + i) < len(vals[y]) and vals[y][x + i].isdigit():
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check = True
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num = num * 10 + int(vals[y][x + i])
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i += 1
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return num if check else -1
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def determine_gear_ratios(vals: list, possible_gears: list) -> list:
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result = list()
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for x, y in possible_gears:
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part_numbers = list()
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for j in (-1, 0, 1):
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tmp_l = check_left_of_symbol(vals, x, y + j)
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tmp_r = check_right_of_symbol(vals, x, y + j)
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tmp_m = vals[y + j][x] if 0 <= y + j < len(vals) and vals[y + j][x].isdigit() else None
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if tmp_m is not None:
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nums = [int("".join([str(x) for x in (tmp_l, tmp_m, tmp_r) if x != -1]))]
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else:
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nums = [x for x in (tmp_l, tmp_r) if x != -1]
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part_numbers.extend(nums)
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if len(part_numbers) == 2:
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result.append(part_numbers[0] * part_numbers[1])
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return result
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def part1(vals: list) -> int:
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return sum_part_numbers(vals)
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def part2(vals: list) -> int:
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possible_gears = find_possible_gears(vals)
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return sum(determine_gear_ratios(vals, possible_gears))
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if __name__ == "__main__":
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vals = read_file()
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print(f"Part 1: {part1(vals)}")
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print(f"Part 2: {part2(vals)}")
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