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use std::{collections::HashMap, fmt::Display, ops::Deref, str::FromStr};
use anyhow::{anyhow, Context, Result};
use crate::Solution;
enum Cmd {
Root,
Parent,
Child(String),
LS(Vec<Entry>),
}
impl FromStr for Cmd {
type Err = anyhow::Error;
fn from_str(s: &str) -> Result<Self, Self::Err> {
let (cmd, arg) = s.trim().split_at(2);
let cmd_arg = (cmd.trim(), arg.trim());
match cmd_arg {
("cd", "/") => Ok(Self::Root),
("cd", "..") => Ok(Self::Parent),
("cd", child) => Ok(Self::Child(child.to_owned())),
("ls", arg) => {
let entries = arg
.trim()
.lines()
.map(Entry::from_str)
.collect::<Result<Vec<_>>>()?;
Ok(Cmd::LS(entries))
}
_ => Err(anyhow!("Failed to parse Command from str: {}", s)),
}
}
}
enum Entry {
Dir(String),
File((String, usize)),
}
impl FromStr for Entry {
type Err = anyhow::Error;
fn from_str(s: &str) -> Result<Self, Self::Err> {
let (entry_type, name) = s
.split_once(' ')
.context(format!("Failed to parse Command from str: {}", s))?;
match entry_type {
"dir" => Ok(Self::Dir(name.to_owned())),
t => Ok(Self::File((name.to_owned(), t.parse()?))),
}
}
}
#[derive(Default, Debug)]
struct FileSystem {
entries: HashMap<Vec<String>, usize>,
cwd: Vec<String>,
}
impl FileSystem {
fn add(&mut self, size: usize) {
self.entries
.entry(self.cwd.to_owned())
.and_modify(|n| *n += size)
.or_insert(size);
}
fn pop_and_add(&mut self) -> Option<String> {
let size = *self.entries.get(&self.cwd).unwrap_or(&0);
let value = self.cwd.pop();
self.add(size);
value
}
fn exec_cmd(&mut self, cmd: Cmd) {
match cmd {
Cmd::Root => self.cwd = vec![],
Cmd::Parent => {
self.pop_and_add();
}
Cmd::Child(d) => self.cwd.push(d),
Cmd::LS(entries) => {
for entry in entries.into_iter() {
match entry {
Entry::File((_, size)) => self.add(size),
Entry::Dir(_) => {}
}
}
}
}
}
}
impl Deref for FileSystem {
type Target = HashMap<Vec<String>, usize>;
fn deref(&self) -> &Self::Target {
&self.entries
}
}
impl FromStr for FileSystem {
type Err = anyhow::Error;
fn from_str(s: &str) -> Result<Self, Self::Err> {
s.split('$')
.filter_map(|l| match l.trim() {
_ if l.is_empty() => None,
l => Some(l),
})
.flat_map(Cmd::from_str)
.collect::<Vec<Cmd>>()
.try_into()
}
}
impl TryFrom<Vec<Cmd>> for FileSystem {
type Error = anyhow::Error;
fn try_from(value: Vec<Cmd>) -> Result<Self, Self::Error> {
let mut fs = Self::default();
for cmd in value {
fs.exec_cmd(cmd)
}
while !fs.cwd.is_empty() {
fs.exec_cmd(Cmd::Parent)
}
Ok(fs)
}
}
impl Display for FileSystem {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
writeln!(f, "path\tsize")?;
for (path, size) in &self.entries {
writeln!(f, "/{}\t{}", path.join("/"), size)?;
}
Ok(())
}
}
pub struct Day7;
impl<'a> Solution<'a> for Day7 {
type Answer1 = usize;
type Answer2 = usize;
const DAY: u8 = 7;
const INPUT: &'a str = include_str!("../input/day_7.txt");
fn part_1(input: &str) -> Result<Self::Answer1> {
let fs: FileSystem = input.parse()?;
Ok(fs.values().filter(|&s| *s < 100_000).sum())
}
fn part_2(input: &str) -> Result<Self::Answer2> {
let fs: FileSystem = input.parse()?;
let used = *fs.get(&Vec::new()).context("Failed to get root size")?;
fs.values()
.filter_map(|&dir_size| match dir_size {
k if used - k < 40_000_000 => Some(k),
_ => None,
})
.min()
.context("No directory found")
}
}
#[cfg(test)]
mod tests {
use super::*;
const TEST_INPUT: &str = indoc::indoc! {r#"
$ cd /
$ ls
dir a
14848514 b.txt
8504156 c.dat
dir d
$ cd a
$ ls
dir e
29116 f
2557 g
62596 h.lst
$ cd e
$ ls
584 i
$ cd ..
$ cd ..
$ cd d
$ ls
4060174 j
8033020 d.log
5626152 d.ext
7214296 k
"#};
#[test]
fn test_part_1_example() -> Result<()> {
Ok(assert_eq!(95437, Day7::part_1(TEST_INPUT)?))
}
#[test]
fn test_part_2_example() -> Result<()> {
Ok(assert_eq!(24933642, Day7::part_2(TEST_INPUT)?))
}
}
|
