aoc-2022-day3.py

from string import ascii_letters
from itertools import zip_longest


def chunk(things, num):
    things = [iter(things)] * num
    return zip_longest(fillvalue=None, *things)


def part1(inp):

    items = []
    vals = {v: k for k, v in enumerate(ascii_letters, start=1)}

    for line in inp:
        a, b = set(line[:int(len(line)/2)]), set(line[int(len(line)/2):])
        if a & b:
            items.append(vals[(a & b).pop()])
    
    return sum(items)


def part2(inp): 

    items = []
    vals = {v: k for k, v in enumerate(ascii_letters, start=1)}
    
    chunks = chunk(inp, 3)
    commons = []

    for c in chunks:
        a, b, c = set(c[0]), set(c[1]), set(c[2])
        if a & b & c:
            commons.append(vals[(a & b & c).pop()])

    return sum(commons)
    


if __name__ == '__main__':

    with open('./input.txt') as f:
        inp = f.read().strip().split('\n')

    print(part1(inp))
    print(part2(inp))