AdventOfCode/2021/day21.py
2021-12-25 19:43:18 +01:00

49 lines
1.2 KiB
Python

from functools import cache
with open("input21.txt") as f:
lines = [line.rstrip() for line in f]
ipos = (int(lines[0].rsplit()[-1]), int(lines[1].rsplit()[-1]))
pos = list(ipos)
scores = [0, 0]
num_rolls = 0
turn = 0
while scores[0] < 1000 and scores[1] < 1000:
roll = sum(range(num_rolls + 1, num_rolls + 4))
num_rolls += 3
pos[turn] = pos[turn] + roll
pos[turn] = pos[turn] - ((pos[turn] - 1) // 10) * 10
scores[turn] += pos[turn]
turn = (turn + 1) % 2
print(min(scores) * num_rolls)
rolls_prob = [
a + b + c for a in range(1, 4) for b in range(1, 4) for c in range(1, 4)
]
@cache
def play(pos, scores, turn):
if scores[0] >= 21:
return 1, 0
if scores[1] >= 21:
return 0, 1
w1, w2 = 0, 0
nturn = (turn + 1) % 2
for r in rolls_prob:
p = pos[turn] + r
p = p - ((p - 1) // 10) * 10
if turn == 0:
npos = p, pos[1]
nscores = scores[0] + p, scores[1]
else:
npos = pos[0], p
nscores = scores[0], scores[1] + p
res1, res2 = play(npos, nscores, nturn)
w1, w2 = w1 + res1, w2 + res2
return w1, w2
print(max(play(ipos, (0, 0), 0)))