138 lines
3.0 KiB
Rust
138 lines
3.0 KiB
Rust
use std::collections::HashSet;
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use std::fs;
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fn main() -> Result<(), Box<dyn std::error::Error>> {
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let input = fs::read_to_string("input")?;
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// Part 1
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let groups = parse_groups(&input)?;
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println!("{}", count_answers(&groups));
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// Part 2
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let groups = parse_group_individuals(&input)?;
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println!("{}", count_individual_answers(&groups));
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Ok(())
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}
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fn parse_groups(input: &str) -> Result<Vec<HashSet<char>>, String> {
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input
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.split("\n\n")
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.map(|group| {
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group
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.chars()
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.filter(|c| *c != '\n')
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.map(|c| {
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if c.is_alphabetic() {
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Ok(c)
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} else {
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Err(format!("Invalid answer: {}", c))
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}
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})
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.collect()
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})
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.collect()
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}
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fn count_answers(groups: &Vec<HashSet<char>>) -> usize {
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groups.iter().map(|group| group.iter().count()).sum()
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}
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fn parse_group_individuals(input: &str) -> Result<Vec<Vec<HashSet<char>>>, String> {
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input
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.split("\n\n")
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.map(|group| {
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group
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.lines()
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.map(|individual| {
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individual
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.chars()
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.map(|c| {
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if c.is_alphabetic() {
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Ok(c)
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} else {
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Err(format!("Invalid answer: {}", c))
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}
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})
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.collect()
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})
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.collect()
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})
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.collect()
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}
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fn count_individual_answers(groups: &Vec<Vec<HashSet<char>>>) -> usize {
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groups
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.iter()
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.map(|group| {
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let mut iter = group.into_iter().cloned();
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let first = iter.next().expect("Must have at least one element");
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iter.fold(first, |cumulative, entry| {
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cumulative.intersection(&entry).copied().collect()
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})
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.len()
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})
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.sum()
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use indoc::indoc;
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#[test]
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fn test_simple() -> Result<(), Box<dyn std::error::Error>> {
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let input = indoc!(
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"abc
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a
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b
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c
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ab
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ac
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a
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a
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a
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a
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b
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"
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);
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let groups = parse_groups(input)?;
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let counts = count_answers(&groups);
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assert_eq!(counts, 11);
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Ok(())
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}
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#[test]
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fn test_simple2() -> Result<(), Box<dyn std::error::Error>> {
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let input = indoc!(
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"abc
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a
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b
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c
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ab
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ac
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a
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a
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a
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a
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b
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"
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);
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let groups = parse_group_individuals(input)?;
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let counts = count_individual_answers(&groups);
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assert_eq!(counts, 6);
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Ok(())
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}
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}
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