80 lines
3.0 KiB
Python
80 lines
3.0 KiB
Python
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import os
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def parse_schematic(file_path):
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"""Reads the engine schematic from a file and returns it as a list of strings."""
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try:
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with open(file_path, 'r') as file:
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return [line.strip() for line in file.readlines()]
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except FileNotFoundError:
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raise Exception(f"File not found: {file_path}")
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def get_adjacent_positions(rows, cols, row, col):
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"""Generates positions adjacent (including diagonally) to the given coordinates."""
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for i in range(max(0, row - 1), min(row + 2, rows)):
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for j in range(max(0, col - 1), min(col + 2, cols)):
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if i != row or j != col:
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yield i, j
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def find_start_of_number(schematic, row, col):
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"""Finds the start position of the number that includes the given digit."""
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while col > 0 and schematic[row][col - 1].isdigit():
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col -= 1
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return row, col
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def extract_full_number(schematic, start_row, start_col):
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"""Extracts the full number starting from the given digit coordinates."""
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start_row, start_col = find_start_of_number(schematic, start_row, start_col)
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number = ''
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rows, cols = len(schematic), len(schematic[0])
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col = start_col
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while col < cols and schematic[start_row][col].isdigit():
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number += schematic[start_row][col]
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schematic[start_row] = schematic[start_row][:col] + '.' + schematic[start_row][col + 1:]
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col += 1
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return int(number) if number else 0
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def find_gears_and_calculate_ratios(schematic):
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"""Finds gears in the schematic and calculates their gear ratios."""
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total_ratio_sum = 0
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rows, cols = len(schematic), len(schematic[0])
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for row in range(rows):
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for col in range(cols):
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if schematic[row][col] == '*':
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part_numbers = []
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for i, j in get_adjacent_positions(rows, cols, row, col):
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if schematic[i][j].isdigit():
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part_number = extract_full_number(schematic, i, j)
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if part_number not in part_numbers:
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part_numbers.append(part_number)
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if len(part_numbers) == 2:
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gear_ratio = part_numbers[0] * part_numbers[1]
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total_ratio_sum += gear_ratio
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print(f"Found gear at line {row + 1} with ratio {gear_ratio}")
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return total_ratio_sum
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def run_tests():
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"""Runs tests on the test file and prints the results."""
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test_schematic = parse_schematic("../test.txt")
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test_result = find_gears_and_calculate_ratios(test_schematic)
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print(f"Test Result: {test_result}")
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assert test_result == 467835, "Test failed: Expected 467835"
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def main():
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"""Main function to process the input file and calculate the sum of gear ratios."""
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try:
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run_tests()
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print("Test passed successfully.")
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schematic = parse_schematic("../input.txt")
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total_ratio_sum = find_gears_and_calculate_ratios(schematic)
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print(f"Total sum of gear ratios: {total_ratio_sum}")
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except Exception as e:
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print(f"Error: {e}")
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if __name__ == "__main__":
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main()
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