rust(day16): Implement day 16
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1 changed files with 148 additions and 0 deletions
148
rust/src/main.rs
148
rust/src/main.rs
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@ -518,6 +518,153 @@ mod day15 {
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}
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}
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mod day16 {
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use std::collections::BTreeSet;
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use std::fmt;
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use std::time::{Duration, Instant};
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type Ticket = Vec<usize>;
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#[derive(PartialEq, Eq, Hash)]
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struct Range {
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from: usize,
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to: usize,
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}
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impl fmt::Debug for Range {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.write_fmt(format_args!("{} - {}", self.from, self.to))
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}
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}
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impl Range {
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fn from(s: &str) -> Self {
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let mut range = s.split("-");
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Self {
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from: range.next().unwrap().parse().unwrap(),
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to: range.next().unwrap().parse().unwrap(),
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}
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}
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}
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#[derive(Debug, PartialEq, Eq, Hash)]
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struct Rule {
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name: String,
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ranges: (Range, Range),
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}
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pub fn run(print: bool) -> Duration {
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let input = std::fs::read_to_string("../inputs/16").unwrap();
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let instant = Instant::now();
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let mut lines = input.lines();
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let mut rules = Vec::new();
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while let Some(line) = lines.next() {
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let mut colon_split = line.split(": ");
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let name = colon_split.next().unwrap().to_string();
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if name.is_empty() {
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break;
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}
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let mut ranges = colon_split.next().unwrap().split(" or ");
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rules.push(Rule {
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name,
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ranges: (
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Range::from(ranges.next().unwrap()),
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Range::from(ranges.next().unwrap()),
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),
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});
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}
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lines.next(); // "your ticket:"
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let your_ticket: Ticket = lines
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.next()
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.unwrap()
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.split(",")
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.flat_map(str::parse)
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.collect();
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lines.next(); // ""
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lines.next(); // "nearby tickets:"
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let mut nearby_tickets: Vec<Ticket> = Vec::new();
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while let Some(line) = lines.next() {
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nearby_tickets.push(line.split(",").flat_map(str::parse).collect());
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}
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let mut part1 = 0;
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let mut valid_tickets = Vec::new();
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for ticket in &nearby_tickets {
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let mut valid = true;
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for field in ticket {
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let rule = rules.iter().find(|rule| {
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(field >= &rule.ranges.0.from && field <= &rule.ranges.0.to)
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|| (field >= &rule.ranges.1.from && field <= &rule.ranges.1.to)
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});
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if rule.is_none() {
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valid = false;
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part1 += field;
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}
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}
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if valid {
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valid_tickets.push(ticket);
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}
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}
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if print {
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dbg!(part1);
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}
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let mut field_possibilities: Vec<_> = (0..your_ticket.len())
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.map(|_| (0..rules.len()).collect::<BTreeSet<_>>())
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.collect();
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for ticket in valid_tickets {
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for (field, possibilities) in ticket.iter().zip(field_possibilities.iter_mut()) {
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for rule_i in possibilities.clone().iter() {
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let rule = &rules[*rule_i];
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if !((field >= &rule.ranges.0.from && field <= &rule.ranges.0.to)
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|| (field >= &rule.ranges.1.from && field <= &rule.ranges.1.to))
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{
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possibilities.remove(&rule_i);
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}
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}
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}
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}
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let mut part2 = 1;
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loop {
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let field_possibility = field_possibilities
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.iter()
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.enumerate()
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.find(|(_, fp)| fp.len() == 1);
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let (i, possibility) = match field_possibility {
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Some((i, v)) => (i, *v.iter().next().take().unwrap()),
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None => break,
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};
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for fp in field_possibilities.iter_mut() {
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fp.remove(&possibility);
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}
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let rule = &rules[possibility].name;
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//println!("{} is {}", rule, your_ticket[i]);
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if rule.starts_with("departure") {
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part2 *= your_ticket[i];
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}
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}
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if print {
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dbg!(part2);
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}
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instant.elapsed()
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}
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}
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fn main() {
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let days = [
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day01::run,
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@ -535,6 +682,7 @@ fn main() {
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day13::run,
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day14::run,
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day15::run,
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day16::run,
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];
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if let Some(day) = std::env::args().nth(1) {
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