advent-of-code/source/year_2020/day_06/mod.rs

//! Day 06 of 2020.

use crate::prelude::*;

/// Get the solution for day 06 of 2020.
pub fn solution() -> Solution {
  Solution::new(Day::new(6, 2020), part_1, part_2).with_expected(6437, 3229)
}

/// The logic to solve part one.
fn part_1(input: &str) -> Result<String> {
  Ok(
    input
      .split("\n\n")
      .map(|group| {
        group
          .replace('\n', "")
          .chars()
          .collect::<HashSet<char>>()
          .len()
      })
      .sum::<usize>()
      .to_string(),
  )
}

/// The logic to solve part two.
fn part_2(input: &str) -> Result<String> {
  Ok(
    input
      .split("\n\n")
      .map(|group| {
        let mut count = 0;
        let possibilities =
          group.replace('\n', "").chars().collect::<HashSet<char>>();
        for character in possibilities {
          if group
            .trim()
            .split('\n')
            .all(|person| person.contains(character))
          {
            count += 1;
          }
        }

        count
      })
      .sum::<usize>()
      .to_string(),
  )
}