Advent of Code 2020

day1.py

#!/usr/local/bin/python

from itertools import combinations
from functools import reduce

n = []
with open('input.txt') as f:
    for l in f.readlines():
        n.append(int(l.rstrip()))

for i in (2, 3):
    for x in combinations(n, i):
        if sum(list(x)) == 2020:
            print(reduce(lambda x, y: x * y, list(x)))

day2.py

#!/usr/local/bin/python

import re

p = re.compile(r"(\d{1,2})-(\d{1,2})\s([a-z]):\s(.*)")

with open("input.txt") as f:
    lines = f.readlines()

prob1_valid_password = 0
prob2_valid_password = 0

for line in lines:

    m = p.match(line)
    (pmin, pmax, letter, passwd) = (
        int(m.group(1)),
        int(m.group(2)),
        m.group(3),
        m.group(4),
    )

    x = passwd.count(letter)
    if x >= pmin and x <= pmax:
        prob1_valid_password += 1

    if bool(passwd[pmin - 1] == letter) != bool(passwd[pmax - 1] == letter):
        prob2_valid_password += 1

print(prob1_valid_password, prob2_valid_password)

day3.py

#!/usr/local/bin/python

from functools import reduce


with open("input.txt") as f:
    lines = f.readlines()

a = []
total = []

for line in lines:
    x = line.rstrip()
    for i in range(1, 15):
        x += x
    a.append(x)

max_x = len(a[0]) - 1
max_y = len(a) - 1

for i in ((1, 1), (1, 3), (1, 5), (1, 7), (2, 1)):

    cord = [0, 0]
    tc = 0

    while cord[0] < max_y:
        cord[0] = cord[0] + i[0]  # down
        cord[1] = cord[1] + i[1]  # right
        if a[cord[0]][cord[1]] == "#":
            tc = tc + 1

    if i == (1, 3):
        # problem 1
        print(tc)

    total.append(tc)

print(reduce(lambda x, y: x * y, list(total)))

day4.py

#!/usr/local/bin/python

import re

rs = lambda r, x: True if re.match(r, x) else False

expected_fields = {
    "byr": lambda x: rs(r"(19[2-9][0-9])|(200[0-3])", x),
    "iyr": lambda x: rs(r"20(1[0-9]|20)", x),
    "eyr": lambda x: rs(r"20(2[0-9]|30)", x),
    "hgt": lambda x: rs(r"((59|6[0-9]|7[0-6])in)|1(([5678][0-9])|(9[0-3]))cm", x),
    "hcl": lambda x: rs(r"^#[0-9a-f]{6}$", x),
    "ecl": lambda x: rs(r"(amb|b[lr][un]|gr[yn]|hzl|oth)", x),
    "pid": lambda x: rs(r"^\d{9}$", x),
}

records = []

with open("input.txt", "r") as f:
    contents = f.read()

for i in re.split(r"\n\n", contents):
    record = {}
    for r in i.rstrip().replace("\n", " ").split(" "):
        (k, v) = r.split(":")
        if k != 'cid':
            record[k] = v

    records.append(record)


valid_passport = []
for r in records:
    if set(r.keys()) == set(expected_fields.keys()):
        valid_passport.append(r)

validated_passport = []
for r in valid_passport:
    valid = True
    for e in expected_fields.keys():
        x = expected_fields[e](r[e])
        if not x:
            valid = False

    if valid:
        validated_passport.append(r)

print(len(valid_passport))
print(len(validated_passport))

day5.py

#!/usr/local/bin/python

from math import floor, ceil

with open("input.txt", "r") as f:
    boarding_passes = [line.rstrip() for line in f]

seats = []

midpoint = lambda x, y: (x + y) / 2

for boarding_pass in boarding_passes:
    row_min,  row_max  = (0, 127)
    seat_min, seat_max = (0, 7)

    for i in range(0, 7):
        if boarding_pass[i] == "F":
            row_max = floor(midpoint(row_min, row_max))
        else:
            row_min = ceil(midpoint(row_min, row_max))

    for i in range(7, 10):
        if boarding_pass[i] == "R":
            seat_min = ceil(midpoint(seat_min, seat_max))
        else:
            seat_max = floor(midpoint(seat_min, seat_max))

    seat_id = row_min * 8 + seat_min
    seats.append(seat_id)

sorted_seats = sorted(seats)
min_seat_id, max_seat_id = (sorted_seats[0], sorted_seats[-1])

all_seats = []
for i in range(min_seat_id, max_seat_id):
    all_seats.append(i)

print(max_seat_id)
print(list(set(all_seats) - set(sorted_seats))[0])

day6.py

#!/usr/local/bin/python

import re

with open('input.txt', 'r') as f:
    contents = f.read().rstrip()

# Problem 1
records = []
for i in re.split(r"\n\n", contents):
    xyzzy = []
    x = i.rstrip().replace('\n', ' ').split(" ")
    for a in x:
        for c in a:
            xyzzy.append(c)

    dropdups = list( dict.fromkeys(xyzzy) )

    records.append(dropdups)

total = 0
for record in records:
    total += len(record)

print(total)


# Problem 2
count = 0

for groups in re.split(r"\n\n", contents):
    group = groups.rstrip().replace('\n', ' ').split(" ")
    count += len(set(group[0]).intersection(*group))

print(count)

day7.py

#!/usr/local/bin/python

import re

with open("input.txt", "r") as f:
    contents = f.read().splitlines()


# Problem 1
bag_type = "shiny gold"
count = 0
hold_bag = []


def bags(bag_type):
    global hold_bag
    is_regex = fr"(?<!^){bag_type}"

    for i in contents:
        if re.search(is_regex, i) is not None:
            extract = re.search(r"^(\w+\s\w+)", i)
            hold_bag.append(extract.group(1))
            bags(extract.group(1))


bags(bag_type)

print(len(list(dict.fromkeys(hold_bag))))

# Problem 2
bags = {}
for line in contents:
    color_regex = re.compile(r"^(\w+\s\w+)\sbags\scontain")
    child_bags_regex = re.compile(r"(\d\s\w+\s\w+)")

    color = color_regex.match(line)
    bags[color.group(1)] = {}

    if "contain no other bags." in line:
        continue

    kv = {}
    child_bags = child_bags_regex.findall(line)
    for found in child_bags:
        s = found.split(" ")
        kv[" ".join(s[1:])] = int(s[0])

    bags[color.group(1)] = kv


def get_bag(bag):
    total = 1

    if len(bags[bag]) == 0:
        return 1

    for color in bags[bag].keys():
        total += int(bags[bag][color]) * get_bag(color)

    return total


print(get_bag("shiny gold") - 1)

day8.py

#!/usr/local/bin/python

import copy

def run_program(asm, opchange=None, printbreak=True):
    seen_location = []

    sp = 0
    acc = 0

    if opchange is not None:
        printbreak = False
        pos = opchange[0]
        oldop = opchange[1]
        newop = opchange[2]

        asm[pos] = asm[pos].replace(oldop, newop)

    while True:

        if sp in seen_location:
            if printbreak:
                print(f"{acc}")
            break

        seen_location.append(sp)

        (op, v) = asm[sp].split(" ")

        if op == "nop":
            sp += 1
        if op == "acc":
            acc += int(v)
            sp += 1
        if op == "jmp":
            sp += int(v)

        if(sp >= len(asm)):
            print(acc)
            break

with open('input.txt', 'r') as f:
    ins = f.read().splitlines()


# Problem 1
run_program(ins)

# Problem 2
index = []
for i in range(len(ins)):
    t = ins[i]
    if 'jmp' in ins[i]:
        index.append((i, "jmp", "nop"))
    if 'nop' in ins[i]:
        index.append((i, "nop", "jmp"))


for opchange in index:
    run_program(copy.deepcopy(ins), opchange, False)

day9.py

#!/usr/local/bin/python

with open("input.txt", "r") as f:
    lines = f.read().splitlines()

# Problem 1
preamble_length = 25
pos = 0

while True:
    preamble = lines[pos : preamble_length + pos]
    next_up = lines[pos + preamble_length]
    sum_table = []

    for x in preamble:
        for y in preamble:
            if x != y:
                sum_table.append(str(int(x) + int(y)))

    if next_up not in sum_table:
        break

    pos += 1

print(next_up)

# Problem 2
array_len = len(lines)
for x in range(array_len):
    block = []
    block.append(int(lines[x]))
    for y in range(x, array_len - 1):
        block.append(int(lines[y + 1]))
        if sum(block) == int(next_up):
            print(min(block) + max(block))
            break