54 lines
1.5 KiB
Python
Executable file
54 lines
1.5 KiB
Python
Executable file
#!/usr/bin/env python3
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# https://adventofcode.com/2024/day/5
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def get_lines(filename: str) -> list:
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with open(filename, "r") as file:
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return [line.strip() for line in file.readlines()]
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def get_rules_and_updates(lines: list) -> tuple:
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rules = {}
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updates = []
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for line in lines:
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if "|" in line:
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a, b = line.split("|")
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if rules.get(b):
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rules[b].append(a)
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else:
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rules[b] = [a]
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elif "," in line:
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updates.append(line.split(","))
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return rules, updates
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def check_validity(rules: dict, update: list) -> bool:
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for position, page_number in enumerate(update):
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if page_number not in rules:
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continue
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# if a number that is supposed to come earlier than our current page_number
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# is included in the rest of the update, it breaks the rules
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for earlier_number in rules[page_number]:
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if earlier_number in update[position:]:
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return False
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return True
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def get_middle_page_sums(rules: dict, updates: list) -> int:
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middle_page_sum = 0
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for update in updates:
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if check_validity(rules, update):
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middle_page_sum += int(update[int(len(update) / 2)])
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return middle_page_sum
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def main():
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# lines = get_lines("sample-input.txt")
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lines = get_lines("input.txt")
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rules, updates = get_rules_and_updates(lines)
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print("Part 1: The sum of valid middle pages is:", get_middle_page_sums(rules, updates))
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if __name__ == '__main__':
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main()
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