Advent of Code 2020: Python Solution Day 6

#adventofcode #algorithms #python #100daysofcode

I am trying this only after few hour of the challenge unlocked. And first part was easy to solve. But for second part, I had to take help from reddit thread, specially here.
From few challenges, I first started with the toy example given there and if all the cases matches on this example input then feed my input to this algorithm and done. Here, day6_test.txt is a example input present on the challenge link. And day6.txt is my input. A repo with output is present at GitHub.

with open("day6_test.txt", "r") as fp:
    lines=fp.readlines()

with open("day6.txt", "r") as fp:
    lines=fp.readlines()

groups = []
group = []
for question in lines:
    if question!="\n":
        group.append(question.split("\n")[0])
    else:
        groups.append(group)
        group=[]
groups.append(group)

# solution to challenge 1
solution_1 = []
for group in groups:
    #print(f"Group: ", group)
    unique_ques = []
    for ques in group:
        unique_ques.extend([uq for uq in ques])

    #print(f"Unique questions: {set(unique_ques)}")
    solution_1.extend(list(set(unique_ques)))
print(f"Solution 1: {len(solution_1)}")


# solution to challenge 2
from collections import Counter
total = 0
for group in groups:
    #print(f"\nGroup: {group}")
    group_size = len(group)
    #print(f"Length of group: {group_size}")

    # make single list of enitire group and count occurence
    counts = Counter("".join(group))
    #print(counts)

    counts = Counter(list(counts.values()))[group_size]
    total+=counts
print(f"Solution 2:", total)

I write blogs about Computer Vision projects on my GitHub page q-viper.github.io and if you got some time please share yours too.

Top comments (6)

Florian Rohrer • Dec 6 '20

Here is my Python solution:

from collections import Counter

with open("input.txt") as f:
    grps = [x.strip().split() for x in f.read().split("\n\n")]

print(sum([len(Counter("".join(g))) for g in grps]))
print(sum([len([v for v in Counter("".join(g)).values() if v == len(g)]) for g in grps]))

Github Link

Viper • Dec 6 '20

So simple yet so tricky.

Olivier Guimbal • Dec 7 '20

My haskell solution

groups = splitWhen (== "") . lines <$> readFile "./data.txt"
part1 = sum . map (length . Set.fromList . intercalate "") <$> groups
part2 = sum . map (Set.size . foldl1 Set.intersection . map Set.fromList)  <$> groups

Viper • Dec 8 '20

Just in 3 lines. It is great.

Gianluca Perrone • Dec 10 '20 • Edited

Ruby two liner

group_answers = File.open("input.txt").read.split("\n\n")
group_answers.reduce(0) { |sum, group| sum + group.split("\n").map { |i| i.split("") }.inject(:&).count }

Viper • Dec 6 '20

Still it is awesome. Thanks for sharing.

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Advent of Code 2020: Python Solution Day 6

Top comments (6)

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