adventofcode2023/day04/sol.py

import sys
from collections import defaultdict

def matches2score(n):
    if n <= 0:
        return 0
    return 2**(n-1)

input = sys.stdin
part1 = 0
card = 0
copies = defaultdict(int)
for line in input:
    card += 1
    _, _, data  = line.partition(": ")
    winners, numbers = data.split("|")
    winners = map(int, winners.split())
    numbers = map(int, numbers.split())

    matches = len(set(winners) & set(numbers))

    s = matches2score(matches)
    print(s)
    part1 += s

    copies[card] += 1 # original copy
    for i in range(matches):
        copies[card+i+1] += copies[card]

print("-")

print(part1)

assert not [i for i,c in copies.items() if c > 0 and i > card]

part2 = sum(copies.values())
print(part2)