Python
(Part 1) omg I can't believe this actually worked first try!
with open('input') as data:
parts = data.read().rstrip().split("\n\n")
ordering_rules = parts[0].split("\n")
updates = parts[1].split("\n")
correct_updates = []
middle_updates = []
def find_relevant_rules(pg_num: str, rules: list[str]) -> list[str] | None:
for rule in rules:
return list(filter(lambda x: x.split("|")[0] == pg_num, rules))
def interpret_rule(rule: str) -> list[str]:
return rule.split("|")
def interpret_update(update: str) -> list[str]:
return update.split(",")
def find_middle_update_index(update: list[str]) -> int:
num_of_elements = len(update)
return num_of_elements // 2
for update in updates:
is_correct = True
for i, page in enumerate(interpret_update(update)):
rules_to_check = find_relevant_rules(page, ordering_rules)
for rule in rules_to_check:
if rule.split("|")[1] in interpret_update(update)[:i]:
is_correct = False
if is_correct:
correct_updates.append(update)
for update in correct_updates:
split_update = update.split(",")
middle_updates.append(int(split_update[find_middle_update_index(split_update)]))
print(sum(middle_updates))
That's kindeof poetic tbh