76 lines
2.0 KiB
Rust
76 lines
2.0 KiB
Rust
use std::collections::HashMap;
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use crate::Day;
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use anyhow::Result;
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pub struct Day07(HashMap<i32, i32>);
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impl Day for Day07 {
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fn init(content: String) -> Result<Self> {
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let mut hm = HashMap::new();
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for n in &content.split(',').map(str::parse).collect::<Result<Vec<_>, std::num::ParseIntError>>()? {
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let entry = hm.entry(*n).or_insert(0);
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*entry += 1;
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}
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Ok(Self(hm))
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}
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fn part1(&self) -> Result<String> {
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let m = self.0.keys().copied().map(
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|x| self.0.iter().map(
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|(n, count)| (x - *n).abs() * (*count)
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).sum::<i32>()
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).min().ok_or_else(|| anyhow::Error::msg("Could not find min"))?;
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Ok(format!("{}", m))
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}
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fn part2(&self) -> Result<String> {
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let max = *self.0.keys().max().ok_or_else(|| anyhow::Error::msg("Could not find max"))?;
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let m = (0..=max).map(
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|x| self.0.iter().map(
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|(n, count)| {
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let n = (x - *n).abs();
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(n * (n + 1) / 2) * (*count)
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}
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).sum::<i32>()
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).min().ok_or_else(|| anyhow::Error::msg("Could not find min"))?;
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Ok(format!("{}", m))
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}
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}
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#[cfg(test)]
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mod tests {
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use crate::day07::Day07;
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use crate::day::Day;
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use anyhow::Result;
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const INPUT: &str = "16,1,2,0,4,2,7,1,2,14";
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#[test]
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fn part1_test() -> Result<()> {
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let d = Day07::init(INPUT.to_string())?;
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assert_eq!("37", d.part1()?);
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Ok(())
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}
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#[test]
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fn part2_test() -> Result<()> {
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let d = Day07::init(INPUT.to_string())?;
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assert_eq!("168", d.part2()?);
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Ok(())
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}
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#[test]
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fn part1_real() -> Result<()> {
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let d = Day07::init(crate::load_input("07")?)?;
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assert_eq!("357353", d.part1()?);
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Ok(())
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}
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#[test]
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fn part2_real() -> Result<()> {
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let d = Day07::init(crate::load_input("07")?)?;
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assert_eq!("104822130", d.part2()?);
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Ok(())
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}
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} |