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#![allow(dead_code)]
#![allow(unused_variables)]
use advent_of_code::prelude::*;
pub struct Todo;
#[derive(Clone, Debug)]
struct LensBox {
lenses: Vec<(String, i64)>,
}
impl LensBox {
fn new() -> Self {
Self { lenses: vec![] }
}
fn insert(&mut self, label: String, focal_length: i64) {
if let Some(idx) = self.lenses.iter().position(|(s, _)| *s == label) {
self.lenses[idx] = (label, focal_length);
} else {
self.lenses.push((label, focal_length));
}
}
fn remove(&mut self, label: &str) {
if let Some(idx) = self.lenses.iter().position(|(s, _)| *s == label) {
self.lenses.remove(idx);
}
}
}
fn hash(s: &str) -> usize {
let mut current = 0usize;
for c in s.bytes() {
current += usize::from(c);
current *= 17;
current %= 256;
}
current
}
pub fn parse(fh: File) -> Result<Vec<String>> {
Ok(parse::split(fh, b',').collect())
}
pub fn part1(ops: Vec<String>) -> Result<i64> {
Ok(ops
.into_iter()
.map(|s| hash(&s))
.sum::<usize>()
.try_into()
.unwrap())
}
pub fn part2(ops: Vec<String>) -> Result<i64> {
let mut boxes = vec![LensBox::new(); 256];
for op in ops {
if let Some(idx) = op.find('=') {
let label = &op[..idx];
let lens_box = hash(label);
let focal_length: i64 = op[(idx + 1)..].parse().unwrap();
boxes[lens_box].insert(label.to_string(), focal_length);
} else if op.ends_with('-') {
let label = &op[..(op.len() - 1)];
let lens_box = hash(label);
boxes[lens_box].remove(label);
}
}
Ok(boxes
.into_iter()
.enumerate()
.map(|(box_num, lens_box)| {
lens_box
.lenses
.iter()
.enumerate()
.map(|(lens_num, (_, focal_length))| {
(i64::try_from(box_num).unwrap() + 1)
* (i64::try_from(lens_num).unwrap() + 1)
* focal_length
})
.sum::<i64>()
})
.sum())
}
#[test]
fn test() {
assert_eq!(
part1(parse(parse::data(2023, 15).unwrap()).unwrap()).unwrap(),
497373
);
assert_eq!(
part2(parse(parse::data(2023, 15).unwrap()).unwrap()).unwrap(),
259356
);
}
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