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#!/usr/bin/python
from copy import copy
from random import randrange
class Entity:
pass
def solve_partn(partn, player_stats, boss_stats):
# We assign numbers 0-4 to the spells
mana_costs = [53, 73, 113, 173, 229]
least_mana = 666666
# 100K attempts turns out to be enough to reliably find the solution
for i in range(100000):
boss = copy( boss_stats)
player = copy(player_stats)
spent_mana = 0
# Timers for "Shield", "Poison" and "Recharge", respectively
timers = [0, 0, 0]
turn = 0
while boss.health > 0 and player.health > 0:
# Already spent too much; this can't be the solution, abort
if spent_mana > least_mana:
break
# Part 2: hard mode: player loses 1 HP at start of their turn
if partn == 2 and turn % 2 == 0:
player.health -= 1
if player.health <= 0:
break
# Apply status effects from past spells
# "Shield"
if timers[0] > 0:
timers[0] -= 1
if timers[0] == 0:
player.armour -= 7
# "Poison"
if timers[1] > 0:
boss.health -= 3
# Did the boss die before any actions were taken?
if boss.health <= 0:
break
timers[1] -= 1
# "Recharge"
if timers[2] > 0:
player.mana += 101
timers[2] -= 1
# Player's turn to cast a spell
if turn % 2 == 0:
# Can we afford to cast any spell? If not, we've lost; abort
if player.mana < min(mana_costs):
break
# Randomly select which spell to cast. Sounds inefficient, but
# works fine: we want to minimize the total mana spent, so we're
# looking for short sequences, which we're very unlikely to miss.
s = -1
while s == -1:
s = randrange(0, 5)
# Can we afford this spell?
if mana_costs[s] > player.mana:
s = -1
# Isn't this spell already active?
if s in [2, 3, 4] and timers[s - 2] > 0:
s = -1
player.mana -= mana_costs[s]
spent_mana += mana_costs[s]
# Apply effect of the spell we've selected
# "Magic Missile"
if s == 0:
boss.health -= 4
# "Drain"
if s == 1:
boss.health -= 2
player.health += 2
# "Shield"
if s == 2:
timers[0] = 6
player.armour += 7
# "Poison"
if s == 3:
timers[1] = 6
# "Recharge"
if s == 4:
timers[2] = 5
# Boss' turn to attack
else: # turn % 2 == 1
player.health -= max(1, boss.damage - player.armour)
turn += 1
# Did we stop because the player won?
if boss.health <= 0:
if spent_mana < least_mana:
least_mana = spent_mana
return least_mana
def main():
# Set up player's stats given in puzzle text
player = Entity()
player.health = 50
player.armour = 0
player.mana = 500
# Read boss' stats from input text file
boss = Entity()
with open("input.txt", "r") as f:
lines = f.read().splitlines()
for i in range(len(lines)): # len(lines) = 2
words = lines[i].split()
if i == 0:
boss.health = int(words[-1])
if i == 1:
boss.damage = int(words[-1])
print("Part 1 solution:", solve_partn(1, player, boss)) # 1269 for me
print("Part 2 solution:", solve_partn(2, player, boss)) # 1309 for me
if __name__ == "__main__":
main()
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