Created
December 2, 2021 15:11
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Solutions to AoC 2021
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import re | |
from itertools import permutations, combinations, count, chain, product | |
from typing import Dict, Tuple, Set, List, Iterator, Optional, Union | |
from collections import defaultdict | |
from functools import lru_cache | |
from math import prod | |
#### FILE INPUT AND PARSING ###################################### | |
# Adapted from Peter Norvigs Advent of Code solutions, https://github.com/norvig/pytudes. | |
def Input(day, parser=str.split, sep='\n') -> list: | |
"For this day's input file, return a list of sections separated by |sep| ad parsed by |parser|." | |
if isinstance(day, int): | |
sections = open(f'advent2021/input{day}.txt').read().rstrip('\n').split(sep) | |
return [parser(section) for section in sections] | |
return [parser(section) for section in day.rstrip('\n').split(sep)] | |
def do(day, *answers) -> List[int]: | |
"E.g., do(3) returns [day3_1(in3), day3_2(in3)]. Verifies `answers` if given." | |
g = globals() | |
got = [] | |
for part in (1, 2): | |
fname = f'day{day}_{part}' | |
if fname in g: | |
got.append(g[fname](g[f'in{day}'])) | |
if len(answers) >= part: | |
assert got[-1] == answers[part - 1], ( | |
f'{fname}(in{day}) got {got[-1]}; expected {answers[part - 1]}') | |
return got | |
################################################################# | |
# Day 1: Sonar Sweep | |
# 1. Count number of numbers larger than the previous | |
# 2. Count number of sum of windows larger than previous sums | |
in1 : List[int] = Input(1, int) | |
def day1_1(nums): | |
return sum(1 for x, y in zip(nums, nums[1:]) if y > x) | |
def day1_2(nums): | |
sums = [sum(win) for win in zip(nums, nums[1:], nums[2:])] | |
return sum(1 for x, y in zip(sums, sums[1:]) if y > x) | |
do(1, 1754, 1789) | |
# Day 2: Dive! | |
# 1. Calculate position from movement instructions | |
# 2. Use aim when calculating the position | |
Instruction = Tuple[str, int] | |
def parse_instr(line) -> Instruction: | |
dir, val = line.split(' ') | |
return dir, int(val) | |
in2 : List[Instruction] = Input(2, parse_instr) | |
def day2_1(instructions): | |
pos, depth = 0, 0 | |
for dir, val in instructions: | |
if dir == 'forward': | |
pos += val | |
elif dir == 'down': | |
depth += val | |
elif dir == 'up': | |
depth -= val | |
return pos * depth | |
def day2_2(instructions): | |
pos, depth, aim = 0, 0, 0 | |
for dir, val in instructions: | |
if dir == 'forward': | |
pos += val | |
depth += aim * val | |
elif dir == 'down': | |
aim += val | |
elif dir == 'up': | |
aim -= val | |
return pos * depth | |
do(2, 1524750,1592426537) | |
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