06.py

from common.util import *
from typing import List

# --- Day 6: Custom Customs ---
# As your flight approaches the regional airport where you'll switch to a much larger plane,
# customs declaration forms are distributed to the passengers.

# The form asks a series of 26 yes-or-no questions marked a through z.
# All you need to do is identify the questions for which anyone in your group answers "yes".
# Since your group is just you, this doesn't take very long.

# However, the person sitting next to you seems to be experiencing a language barrier and asks if you can help.
# For each of the people in their group, you write down the questions for which they answer "yes", one per line. For example:

# abcx
# abcy
# abcz
# In this group, there are 6 questions to which anyone answered "yes": a, b, c, x, y, and z.
# (Duplicate answers to the same question don't count extra; each question counts at most once.)

# Another group asks for your help, then another, and eventually you've collected answers from every group on the plane
# (your puzzle input). Each group's answers are separated by a blank line, and within each group,
# each person's answers are on a single line. For example:

# abc

# a
# b
# c

# ab
# ac

# a
# a
# a
# a

# b
# This list represents answers from five groups:

# The first group contains one person who answered "yes" to 3 questions: a, b, and c.
# The second group contains three people; combined, they answered "yes" to 3 questions: a, b, and c.
# The third group contains two people; combined, they answered "yes" to 3 questions: a, b, and c.
# The fourth group contains four people; combined, they answered "yes" to only 1 question, a.
# The last group contains one person who answered "yes" to only 1 question, b.
# In this example, the sum of these counts is 3 + 3 + 3 + 1 + 1 = 11.

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


def part1(data: List[str]) -> int:

    count = 0
    questions = set()

    for i, item in enumerate(data):

        if item != "":
            for char in item:
                questions.add(char)

        if i == len(data) - 1 or item == "":
            count += len(questions)
            questions = set()

    return count


data = get_data("day06", line_parser)
print(part1(data))


# --- Part Two ---
# As you finish the last group's customs declaration, you notice that you misread one word in the instructions:

# You don't need to identify the questions to which anyone answered "yes";
# you need to identify the questions to which everyone answered "yes"!

# Using the same example as above:

# abc

# a
# b
# c

# ab
# ac

# a
# a
# a
# a

# b
# This list represents answers from five groups:

# In the first group, everyone (all 1 person) answered "yes" to 3 questions: a, b, and c.
# In the second group, there is no question to which everyone answered "yes".
# In the third group, everyone answered yes to only 1 question, a. Since some people did not answer "yes" to b or c, they don't count.
# In the fourth group, everyone answered yes to only 1 question, a.
# In the fifth group, everyone (all 1 person) answered "yes" to 1 question, b.
# In this example, the sum of these counts is 3 + 0 + 1 + 1 + 1 = 6.

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


def part2(data: List[str]) -> int:
    from functools import reduce

    count = 0
    questions = []

    for i, item in enumerate(data):
        temp_set = set()

        if item != "":
            for char in item:
                temp_set.add(char)
            questions.append(temp_set)
            temp_set = set()

        if i == len(data) - 1 or item == "":
            count += len(reduce(lambda a, b: a & b, questions))
            questions = []

    return count


data = get_data("day06", line_parser)
print(part2(data))