day 3 (help)

src/bin/day03.rs

@@ -0,0 +1,12 @@
+use aoc_2025::day03;
+use color_eyre::Report;
+
+fn main() -> Result<(), Report> {
+    color_eyre::install()?;
+    let data = day03::data("inputs/day03.txt")?;
+    let code1 = day03::part1(&data)?;
+    let code2 = day03::part2(&data)?;
+    println!("code1: {code1}");
+    println!("code2: {code2}");
+    Ok(())
+}

src/day03.rs

@@ -0,0 +1,128 @@
+use color_eyre::{Report, eyre::ContextCompat};
+use std::{
+    fs::File,
+    io::{self, BufRead, BufReader},
+};
+
+const BATTERIES: usize = 12;
+
+pub struct BatteryBank {
+    biggest_sorted: Vec<u8>,
+    batteries: Vec<u8>,
+}
+
+impl TryFrom<String> for BatteryBank {
+    type Error = Report;
+    fn try_from(value: String) -> Result<Self, Self::Error> {
+        let digits = value
+            .chars()
+            .map(|v| v.to_string().parse::<u8>())
+            .collect::<Result<Vec<u8>, std::num::ParseIntError>>()?;
+        let mut sorted_list = digits.clone();
+        sorted_list.sort();
+        sorted_list.reverse();
+        sorted_list.dedup();
+
+        Ok(Self {
+            batteries: digits,
+            biggest_sorted: sorted_list,
+        })
+    }
+}
+
+impl BatteryBank {
+    fn try_value_part1(&self, index: usize) -> Result<Option<u64>, Report> {
+        let value = self.biggest_sorted.get(index).context("out of bounds")?;
+        let index = self.batteries.iter().position(|x| x == value).unwrap();
+        let (_, split) = self.batteries.split_at(index + 1);
+        if split.is_empty() {
+            return Ok(None);
+        }
+        let mut split = split.to_vec();
+        split.sort();
+        let biggest = split.last().unwrap();
+
+        Ok(Some((value * 10) as u64 + *biggest as u64))
+    }
+    fn part1(&self) -> Result<u64, Report> {
+        let len = self.biggest_sorted.len();
+        for i in 0..len {
+            if let Some(v) = self.try_value_part1(i)? {
+                return Ok(v);
+            }
+        }
+        Ok(0)
+    }
+
+    fn part2(&self) -> Result<u64, Report> {
+        let mut progress = vec![];
+        let len = self.batteries.len();
+        for (i, value) in self.batteries.iter().enumerate() {
+            while let Some(last) = progress.last()
+                && *last < value
+                && progress.len() + (len - i) > BATTERIES
+            {
+                progress.pop();
+            }
+
+            if progress.len() < BATTERIES {
+                progress.push(value);
+            }
+        }
+        println!("value: {progress:?} {}", progress.len());
+        let mut num = 0;
+        for (i, v) in progress.iter().enumerate() {
+            num += **v as u64 * 10_u64.pow(progress.len() as u32 - i as u32 - 1);
+        }
+        // println!("{num}");
+        Ok(num)
+    }
+}
+
+pub fn part1(data: &[BatteryBank]) -> Result<u64, Report> {
+    Ok(data
+        .iter()
+        .map(|v| v.part1())
+        .collect::<Result<Vec<u64>, Report>>()?
+        .iter()
+        .sum::<u64>())
+}
+
+pub fn part2(data: &[BatteryBank]) -> Result<u64, Report> {
+    // let first = BatteryBank::try_from(String::from("818181911112111"))?.part2()?;
+    Ok(data
+        .iter()
+        .map(|v| v.part2())
+        .collect::<Result<Vec<u64>, Report>>()?
+        .iter()
+        .sum::<u64>())
+}
+pub fn data(filepath: &str) -> Result<Vec<BatteryBank>, Report> {
+    let file = File::open(filepath)?;
+    let bufreader = BufReader::new(file);
+    let banks = bufreader
+        .lines()
+        .collect::<Result<Vec<String>, io::Error>>()?
+        .into_iter()
+        .map(BatteryBank::try_from)
+        .collect::<Result<Vec<BatteryBank>, Report>>()?;
+    Ok(banks)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use criterion::Criterion;
+    use criterion_macro::criterion;
+
+    #[criterion]
+    fn bench_part1(b: &mut Criterion) {
+        let data = data("inputs/day03.txt").unwrap();
+        b.bench_function("day03-part1", |b| b.iter(|| part1(&data).unwrap()));
+    }
+    #[criterion]
+    fn bench_part2(b: &mut Criterion) {
+        let data = data("inputs/day03.txt").unwrap();
+        b.bench_function("day03-part2", |b| b.iter(|| part2(&data).unwrap()));
+    }
+}

src/lib.rs

@@ -4,3 +4,4 @@
 extern crate test;
 pub mod day01;
 pub mod day02;
+pub mod day03;