aoc/2020/22/22.py
2020-12-22 00:18:42 -06:00

78 lines
1.6 KiB
Python

with open("input_sample.txt") as f:
p1, p2 = f.read().split('\n\n')
p1 = p1.split('\n')[1:]
p2 = p2.split('\n')[1:]
p1 = list(map(int, p1))
p2 = list(map(int, p2))
i = 1
while True:
#print(f"-- Round {i} --")
#print("Player 1's deck: ", p1)
#print("Player 2's deck: ", p2)
c1 = p1.pop(0)
c2 = p2.pop(0)
#print("Player 1 plays: ",c1)
#print("Player 2 plays: ",c2)
if c1 > c2:
#print("Player 1 wins the round!")
p1 += [c1, c2]
else:
#print("Player 2 wins the round!")
p2 += [c2, c1]
i += 1
#print(p1,p2)
if len(p1) == 0:
winner = p2
break
if len(p2) == 0:
winner = p1
break
part1 = 0
for i, card in enumerate(reversed(winner)):
part1 += (i+1)*card
print(part1)
with open("input.txt") as f:
p1, p2 = f.read().split('\n\n')
p1 = p1.split('\n')[1:]
p2 = p2.split('\n')[1:]
p1 = list(map(int, p1))
p2 = list(map(int, p2))
def play(p1, p2):
seen = set()
while True:
# does p1 auto-win?
state = (tuple(p1), tuple(p2))
if state in seen:
return 1, p1
seen.add(state)
# draw cards
c1 = p1.pop(0)
c2 = p2.pop(0)
# should we recurse?
if len(p1) >= c1 and len(p2) >= c2: # play recursive round
winner, deck = play(p1[:c1],p2[:c2]) # copy that many cards
if winner == 1:
p1 += [c1, c2]
else: # winner == 2
p2 += [c2, c1]
else: # play normal round
if c1 > c2:
p1 += [c1, c2]
else: # c2 > c1
p2 += [c2, c1]
# does anyone win by normal rules?
if len(p1) == 0:
return 2, p2
break
if len(p2) == 0:
return 1, p1
i, winner = play(p1, p2)
part2 = 0
for i, card in enumerate(reversed(winner)):
part2 += (i+1)*card
print(part2)