Keenan Tims
968d795720
* I misunderstood the problem and thought we were asked for the distance between the numbers' positions, not their values. Removed remnants of that. * Move to struct-oriented solution * Fix clippys and unnecessary code
106 lines
2.4 KiB
Rust
106 lines
2.4 KiB
Rust
use std::collections::HashMap;
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use std::fs::File;
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use std::io::{BufRead, BufReader, Lines};
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use std::iter::zip;
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use std::time::Instant;
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// BOILERPLATE
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type InputIter = Lines<BufReader<File>>;
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fn get_input() -> InputIter {
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let f = File::open("input").unwrap();
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let br = BufReader::new(f);
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br.lines()
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}
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fn main() {
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let start = Instant::now();
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let ans1 = problem1(get_input());
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let duration = start.elapsed();
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println!("Problem 1 solution: {} [{}s]", ans1, duration.as_secs_f64());
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let start = Instant::now();
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let ans2 = problem2(get_input());
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let duration = start.elapsed();
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println!("Problem 2 solution: {} [{}s]", ans2, duration.as_secs_f64());
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}
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struct Locations {
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left: Vec<u64>,
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right: Vec<u64>,
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}
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impl<T: BufRead> From<Lines<T>> for Locations {
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fn from(input: Lines<T>) -> Self {
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let mut left = Vec::new();
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let mut right = Vec::new();
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for line in input.map(|i| i.unwrap()) {
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let parts: Vec<&str> = line.split_ascii_whitespace().collect();
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left.push(parts[0].parse::<u64>().unwrap());
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right.push(parts[1].parse::<u64>().unwrap());
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}
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Self { left, right }
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}
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}
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impl Locations {
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fn sort(&mut self) {
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self.left.sort();
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self.right.sort();
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}
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fn right_count(&self) -> HashMap<u64, u64> {
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let mut right_count: HashMap<u64, u64> = HashMap::new();
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for rval in &self.right {
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right_count.insert(*rval, *right_count.get(rval).unwrap_or(&0) + 1);
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}
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right_count
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}
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}
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// PROBLEM 1 solution
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fn problem1<T: BufRead>(input: Lines<T>) -> u64 {
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let mut locations = Locations::from(input);
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locations.sort();
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zip(locations.left, locations.right)
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.map(|(l, r)| u64::abs_diff(l, r))
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.sum()
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}
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// PROBLEM 2 solution
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fn problem2<T: BufRead>(input: Lines<T>) -> u64 {
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let locations = Locations::from(input);
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let right_count = locations.right_count();
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locations
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.left
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.iter()
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.map(|l| l * right_count.get(l).unwrap_or(&0))
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.sum::<u64>()
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}
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#[cfg(test)]
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mod tests {
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use crate::*;
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use std::io::Cursor;
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const EXAMPLE: &str = &"3 4
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4 3
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2 5
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1 3
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3 9
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3 3";
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#[test]
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fn problem1_example() {
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let c = Cursor::new(EXAMPLE);
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assert_eq!(problem1(c.lines()), 11);
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}
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#[test]
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fn problem2_example() {
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let c = Cursor::new(EXAMPLE);
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assert_eq!(problem2(c.lines()), 31);
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}
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}
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