aoc24/day5/solution.py
2024-12-05 09:53:05 +01:00

49 lines
No EOL
1.1 KiB
Python

import sys
def main():
lines = sys.stdin.read().splitlines()
order_rules = set()
updates = []
i = 0
n = len(lines)
while i < n and lines[i].strip():
line = lines[i].strip()
if '|' in line:
x, y = line.split('|')
x = int(x)
y = int(y)
order_rules.add((x, y))
i += 1
while i < n and not lines[i].strip():
i += 1
while i < n:
line = lines[i].strip()
if line:
update = [int(x) for x in line.split(',')]
updates.append(update)
i += 1
middle_pages = []
for update in updates:
position = {page: idx for idx, page in enumerate(update)}
valid = True
for x, y in order_rules:
if x in position and y in position:
if position[x] >= position[y]:
valid = False
break
if valid:
mid_index = len(update) // 2
middle_page = update[mid_index]
middle_pages.append(middle_page)
total = sum(middle_pages)
print(total)
if __name__ == "__main__":
main()