145 lines
3.8 KiB
Rust
145 lines
3.8 KiB
Rust
#![feature(test)]
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extern crate test;
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use std::ops::{Index, IndexMut};
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use aoc2022::{boilerplate, common::*};
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const DAY: usize = 7;
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enum Node<'a> {
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File(&'a str, usize),
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Dir(&'a str, Vec<Box<Node<'a>>>, usize),
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}
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impl<'a> IndexMut<&str> for Node<'a> {
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fn index_mut(&mut self, index: &str) -> &mut Node<'a> {
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match self {
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Self::Dir(_, contents, _) => {
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contents.iter_mut().find(|d| matches!(***d, Self::Dir(name, _, _) if name == index)).expect("File not found")
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}
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Self::File(name, _) => panic!("Can’t index into a file ({name})"),
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}
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}
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}
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impl<'a> Index<&str> for Node<'a> {
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type Output = Self;
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fn index(&self, index: &str) -> &Self::Output {
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match self {
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Self::Dir(_, contents, _) => {
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contents.iter().find(|&d| matches!(**d, Self::Dir(name, _, _) if name == index)).expect("File not found")
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}
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Self::File(name, _) => panic!("Can’t index into a file ({name})"),
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}
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}
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}
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fn parse_input(raw: &str) -> Node<'_> {
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let mut pwd = Vec::<&str>::new();
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let mut fs = Node::Dir("/", Vec::new(), 0);
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for cmd in raw.trim_start_matches("$ cd /\n$ ").split("$ ") {
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let mut lines = cmd.lines();
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match lines.next().and_then(|s| s.split_once(' ')) {
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Some(("cd", "..")) => {
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pwd.pop();
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}
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Some(("cd", dir)) => pwd.push(dir),
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// ls
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_ => {
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let mut cd = &mut fs;
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for p in pwd.iter() {
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cd = &mut cd[p];
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}
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match cd {
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Node::Dir(_, contents, _) => {
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for line in lines {
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match line.split_once(' ') {
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Some(("dir", d)) => contents.push(Box::new(Node::Dir(d, Vec::new(), 0))),
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Some((size, name)) => contents.push(Box::new(Node::File(name, size.parse().unwrap()))),
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_ => unreachable!("Invalid directory contents: {line}"),
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}
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}
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}
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Node::File(_, _) => unreachable!("Can’t `ls` file contents"),
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}
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}
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};
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}
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compute_dir_size(&mut fs);
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fs
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}
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fn compute_dir_size(node: &mut Node<'_>) -> usize {
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match node {
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Node::File(_, s) => *s,
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Node::Dir(_, c, size) => {
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*size = c.iter_mut().map(|d| compute_dir_size(d)).sum();
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*size
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}
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}
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}
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fn part1(parsed: &Node<'_>) -> usize {
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let mut sizes = Vec::new();
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dir_sizes(parsed, &mut sizes);
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sizes.into_iter().filter(|&s| s <= 100_000).sum()
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}
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fn dir_sizes(node: &Node<'_>, sizes: &mut Vec<usize>) {
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if let Node::Dir(_, contents, size) = node {
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sizes.push(*size);
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for c in contents {
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dir_sizes(c, sizes);
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}
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}
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}
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fn part2(parsed: &Node<'_>) -> usize {
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let needed_space = 30000000 - (70000000 - if let Node::Dir(_, _, s) = parsed { s } else { unreachable!() });
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let mut sizes = Vec::new();
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dir_sizes(parsed, &mut sizes);
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sizes.into_iter().filter(|&s| s >= needed_space).min().unwrap()
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}
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boilerplate! {
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TEST_INPUT == "$ cd /
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$ ls
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dir a
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14848514 b.txt
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8504156 c.dat
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dir d
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$ cd a
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$ ls
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dir e
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29116 f
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2557 g
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62596 h.lst
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$ cd e
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$ ls
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584 i
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$ cd ..
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$ cd ..
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$ cd d
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$ ls
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4060174 j
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8033020 d.log
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5626152 d.ext
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7214296 k",
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tests: {
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part1: { TEST_INPUT => 95437 },
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part2: { TEST_INPUT => 24933642 },
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},
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bench1 == 1667443,
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bench2 == 0,
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bench_parse: node_name => "/",
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}
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#[cfg(test)]
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fn node_name<'a>(n: &Node<'a>) -> &'a str {
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match n {
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Node::Dir(name, _, _) => name,
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Node::File(name, _) => name,
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}
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}
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