adventofcode/2020/13.py

#!/usr/bin/env python

from aoc import get_input # AoC

data = get_input(13).splitlines()

time = int(data[0])

busses = []
for busid in data[1].split(","):
    if(busid != "x"):
        busses.append(int(busid))

busses.sort()


def getTimestamp(busid, i):
    return busid * i


bustimes = dict()

for busid in busses:
    i = 0
    bustimes[busid] = []
    while True:
        timestamp = getTimestamp(busid, i)
        bustimes[busid].append(timestamp)

        if(timestamp > time):
            break
        else:
            i += 1
            continue

waittimes = dict()
for busid, t in bustimes.items():
    high = max(t)
    waittimes[busid] = high - time

bestbusid = min(waittimes, key=waittimes.get)

thing = bestbusid * waittimes[bestbusid]

# Part 2

bus = dict()
i = 0
for busid in data[1].split(","):
    if(busid != "x"):
        bus[i] = int(busid)

    i += 1

from sympy.ntheory.modular import crt

pos = []
buss = []
for i, busid in bus.items():
    pos.append(i)
    buss.append(busid)

hello = crt(buss, pos)

thething = hello[1] - hello[0]


print("Part1", thing)
print("Part2", thething)