return a, b
# f(x) = ax + b
# Returns the position of card x after applying the shuffle
def apply_shuffle(a, b, x, size):
return (a * x + b) % size
# Returns which card will be on position x after applying the shuffle
def apply_shuffle_inverted(a, b, x, size):
return ((x - b) * modular_inverse(a, size)) % size
# g(f(x)) = cf(x) + d = cax + cb + d
def combine_functions(a, b, c, d, size):
return (c * a) % size, (c * b + d) % size
def modular_inverse(x, size):
ret, _ = modular_exponentiation(x, 0, size - 2, size)
return ret
def modular_exponentiation(a, b, iterations, size):
if iterations == 1:
return a, b
elif iterations % 2 == 0:
a, b = combine_functions(a, b, a, b, size)
return modular_exponentiation(a, b, iterations / 2, size)
else:
c, d = modular_exponentiation(a, b, iterations - 1, size)
return combine_functions(a, b, c, d, size)
aoc.run_lines(main, "day22.txt")
resources[ORE] = TRILLION
resources[FUEL] = -part2
nanofactory(reactions, resources)
ore_remaining = resources[ORE]
if ore_remaining <= 0:
part2 -= 1
break
else:
part2 += max(1, int(ore_remaining / ore_per_fuel))
return part1, part2
def nanofactory(reactions, resources):
while any(r != ORE and resources[r] < 0 for r in resources):
for target in resources:
if resources[target] < 0:
new_resources = False
for reaction in reactions:
if target in reaction[1]:
reaction_count = max(1, int(-resources[target] / reaction[1][target]))
for item in reaction[0]:
if item not in resources:
new_resources = True
resources[item] -= reaction[0][item] * reaction_count
for item in reaction[1]:
resources[item] += reaction[1][item] * reaction_count
if new_resources:
break
aoc.run_lines(main, "day14.txt")
return part1, part2
def run_program(program, instruction_to_flip):
seen_instructions = []
nop_jmp_counter = 0
program_pointer = 0
acc = 0
while program_pointer not in seen_instructions and program_pointer < len(program):
seen_instructions.append(program_pointer)
instruction = program[program_pointer][0]
value = program[program_pointer][1]
program_pointer += 1
if nop_jmp_counter == instruction_to_flip:
if instruction == "nop":
instruction = "jmp"
elif instruction == "jmp":
instruction = "nop"
if instruction == "acc":
acc += value
elif instruction == "jmp":
program_pointer += value - 1
nop_jmp_counter += 1
elif instruction == "nop":
nop_jmp_counter += 1
return acc, program_pointer >= len(program)
aoc.run_lines(main, "day08.txt")
