day9a.py

#!/usr/bin/env python3

import sys
import re

class Node:

	def __init__ (self, value):
		self.value = value
		self.next = None
		self.prev = None

	def __repr__ (self):
		return repr(self.value)

class Ring:

	def __init__ (self):

		self.current = Node(0)
		self.current.next = self.current
		self.current.prev = self.current

	def insert (self, node):

		node.prev = self.current
		node.next = self.current.next

		self.current.next.prev = node
		self.current.next = node

		self.current = node

	def seek (self, n):

		if n < 0:
			while n < 0:
				self.current = self.current.prev
				n += 1
		else:
			while 0 < n:
				self.current = self.current.next
				n -= 1

	def pop (self):

		value = self.current.value

		self.current.prev.next = self.current.next
		self.current.next.prev = self.current.prev

		self.current = self.current.next

		return value

	def __repr__ (self):

		outp = []

		curr = self.current

		while True:

			outp.append(repr(curr))
			curr = curr.next

			if curr == self.current:
				break

		return repr(outp)

def play (nplayers, highest):

	ring = Ring()

	scores = {}

	player = 0

	for i in range(1, highest + 1):

		if i % 23 == 0:
			if player not in scores:
				scores[player] = 0

			ring.seek(-7)
			scores[player] += i + ring.pop()

		else:
			ring.seek(1)
			ring.insert(Node(i))

		player = (player + 1) % nplayers

	#print(ring, scores, scores[max(scores)])

	return scores[max(scores)]


def parse (s):

	specre = re.compile('(\d+) players; last marble is worth (\d+) points')

	return map(int, specre.match(s).group(1, 2))

def main ():
	nplayers, highest = parse(sys.stdin.read())
	print(play(nplayers, highest))

if __name__ == '__main__':
	assert(play(9, 25) == 32)
	assert(play(10, 1618) == 8317)
	assert(play(13, 7999) == 146373)
	assert(play(17, 1104) == 2764)
	assert(play(21, 6111) == 54718)
	assert(play(30, 5807) == 37305)
	main()