Advent of Code 2020 Day 6

Author

Nathan Moore

— Day 6: Custom Customs —

Customs forms are being handed out on the flight and you need to work out who answers yes to how many questions.

For each group, count the number of questions to which anyone answered “yes”. What is the sum of those counts?

with open('data-2020-06.txt', 'r') as f:
    qq = f.read()

# split groups
qq_split = qq.split("\n\n")

set() gives unique letters

# replace \n with nothing, since we're interested in group as a whole
# set provides us with unique items
# len gives us how many answers
part_one = [len(set(x.replace("\n", ""))) for x in qq_split]

# part one answer
sum(part_one)

— Part Two —

We don’t have to work out any person answered yes, we have to count all who answered yes.

For each group, count the number of questions to which everyone answered “yes”. What is the sum of those counts?

qq_groups = [x.replace("\n", " ") for x in qq_split]

# how many people are there in each group
qq_num = [x.count(" ")+1 for x in qq_groups]

# https://stackoverflow.com/questions/1155617/count-the-number-occurrences-of-a-character-in-a-string
from collections import Counter

# do the count
counter = [Counter(x) for x in qq_groups]

# now we need to combine these with the number of groups
# count_num = [value == nn for cc, nn in zip(counter, qq_num) for value in cc.values()]
count_num = [list(cc.values()).count(nn) for cc, nn in zip(counter, qq_num)]

sum(count_num)