37 lines
1.2 KiB
Python
37 lines
1.2 KiB
Python
import aoclib
|
|
import math
|
|
|
|
DAY = 13
|
|
TEST_SOLUTION_PART1 = 295
|
|
TEST_SOLUTION_PART2 = 1068781
|
|
|
|
|
|
def part1(test_mode=False):
|
|
my_input = aoclib.getInputAsArraySplit(day=DAY, split_char=",", test=test_mode)
|
|
|
|
my_arrival = int(my_input[0][0])
|
|
bus_ids = [int(i) for i in my_input[1] if i != 'x']
|
|
waiting_times = [i - my_arrival % i for i in bus_ids]
|
|
min_waiting_time = min(waiting_times)
|
|
|
|
return min_waiting_time * bus_ids[waiting_times.index(min_waiting_time)]
|
|
|
|
|
|
def part2(test_mode=False):
|
|
my_input = aoclib.getInputAsArraySplit(day=DAY, split_char=",", test=test_mode)
|
|
|
|
bus_ids = {-i: int(v) for i, v in enumerate(my_input[1]) if v != 'x'}
|
|
lowest_common_multiple = math.lcm(*bus_ids.values())
|
|
base_multipliers = [lowest_common_multiple // interval for interval in bus_ids.values()]
|
|
modular_multiplicative_inverses = [
|
|
pow(base_multiplier, -1, interval)
|
|
for base_multiplier, interval
|
|
in zip(base_multipliers, bus_ids.values())
|
|
]
|
|
|
|
return sum(
|
|
offset * multiplier * mmi
|
|
for offset, multiplier, mmi
|
|
in zip(bus_ids.keys(), base_multipliers, modular_multiplicative_inverses)
|
|
) % lowest_common_multiple
|