134 lines
3.5 KiB
Rust
134 lines
3.5 KiB
Rust
use std::io::{self, BufRead};
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struct Diagnostics<const N: usize> {
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report: Vec<String>,
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}
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impl<const N: usize> Diagnostics<N> {
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fn gamma_rate(&self) -> u32 {
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u32::from_str_radix(&self.most_common_bits(), 2).unwrap()
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}
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fn epsilon_rate(&self) -> u32 {
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0xfff ^ self.gamma_rate()
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}
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fn oxygen_generator_rating(&self) -> u32 {
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u32::from_str_radix(&self.most_common_value(), 2).unwrap()
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}
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fn co2_scrubber_rating(&self) -> u32 {
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u32::from_str_radix(&self.least_common_value(), 2).unwrap()
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}
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fn count_bit(&self, values: &Vec<String>, bit: usize) -> (usize, usize) {
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values
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.iter()
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.fold((0, 0), |acc, x| match x.chars().nth(bit).unwrap() {
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'0' => (acc.0 + 1, acc.1),
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'1' => (acc.0, acc.1 + 1),
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_ => acc,
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})
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}
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fn most_common_bits(&self) -> String {
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(0..N)
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.map(|i| {
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let (zeros, ones) = self.count_bit(&self.report, i);
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if zeros > ones {
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'0'
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} else {
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'1'
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}
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})
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.collect()
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}
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fn filter_values(
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&self,
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values: Vec<String>,
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bit: usize,
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predicate: impl Fn(usize, usize) -> bool,
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) -> Vec<String> {
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if values.len() <= 1 {
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return values;
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}
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let (zeros, ones) = self.count_bit(&values, bit);
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values
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.iter()
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.filter(|x| match x.chars().nth(bit).unwrap() {
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'0' if !predicate(zeros, ones) => true,
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'1' if predicate(zeros, ones) => true,
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_ => false,
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})
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.cloned()
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.collect()
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}
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fn most_common_value(&self) -> String {
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(0..N)
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.fold(self.report.clone(), |r, i| {
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self.filter_values(r, i, |zeros, ones| ones >= zeros)
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})
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.first()
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.unwrap()
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.clone()
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}
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fn least_common_value(&self) -> String {
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(0..N)
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.fold(self.report.clone(), |r, i| {
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self.filter_values(r, i, |zeros, ones| ones < zeros)
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})
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.first()
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.unwrap()
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.clone()
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}
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}
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fn main() {
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const INPUT: &str = include_str!("../inputs/day3.txt");
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let report: Vec<String> = io::Cursor::new(INPUT).lines().map(|l| l.unwrap()).collect();
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let diagnostics = Diagnostics::<12> { report };
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println!(
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"gamma rate {} epsilon rate {}",
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diagnostics.gamma_rate(),
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diagnostics.epsilon_rate()
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);
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println!(
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"solution {}",
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diagnostics.gamma_rate() * diagnostics.epsilon_rate()
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);
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println!(
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"oxygen generator rating {} CO2 scrubber rating {}",
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diagnostics.oxygen_generator_rating(),
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diagnostics.co2_scrubber_rating()
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);
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println!(
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"solution {}",
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diagnostics.oxygen_generator_rating() * diagnostics.co2_scrubber_rating()
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);
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}
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#[test]
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fn oxygen_generator_rating() {
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let report = vec![
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"00100".to_string(),
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"11110".to_string(),
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"10110".to_string(),
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"10111".to_string(),
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"10101".to_string(),
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"01111".to_string(),
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"00111".to_string(),
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"11100".to_string(),
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"10000".to_string(),
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"11001".to_string(),
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"00010".to_string(),
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"01010".to_string(),
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];
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let diagnostics = Diagnostics::<5> { report };
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assert_eq!(diagnostics.most_common_value(), "10111");
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}
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