98 lines
3.4 KiB
Rust
98 lines
3.4 KiB
Rust
#![allow(dead_code)]
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use std::fs::File;
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use std::io;
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use std::io::BufRead;
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use std::path::Path;
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use std::time::Instant;
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fn main() {
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let now = Instant::now();
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part_one();
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let part_one_duration = now.elapsed();
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part_two();
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let part_two_duration = now.elapsed();
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println!(
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"p1: {}ms, p2: {}ms",
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part_one_duration.as_millis(),
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(part_two_duration - part_one_duration).as_millis()
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);
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}
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fn read_lines<P>(filename: P) -> io::Result<io::Lines<io::BufReader<File>>>
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where
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P: AsRef<Path>,
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{
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// note that this discards a final newline
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let file = File::open(filename)?;
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Ok(io::BufReader::new(file).lines())
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}
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fn part_one() {
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if let Ok(lines) = read_lines("./inputs/input") {
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let mut sum = 0;
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let mut stack: Vec<u32> = vec![0];
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for line in lines {
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if let Ok(command) = line {
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match command.as_str() {
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"$ cd /" => continue, // skip start
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"$ ls" => continue, // we can assume this if we're not moving between directories
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s if s.starts_with("dir ") => continue, // we'll get there when we `cd`
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"$ cd .." => {
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let f = stack.pop().unwrap();
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if f < 100000 {
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sum += f
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}
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let last_on_stack = stack.len() - 1;
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stack[last_on_stack] += f;
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}
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s if s.starts_with("$ cd ") => {
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stack.push(0);
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}
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s => {
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// otherwise it must be a file
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let mut sp = s.split(" ");
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let last_on_stack = stack.len() - 1;
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stack[last_on_stack] += sp.next().unwrap().parse::<u32>().unwrap();
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}
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};
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}
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}
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println!("{:?}", sum);
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}
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}
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fn part_two() {
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if let Ok(lines) = read_lines("./inputs/input") {
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let mut stack: Vec<u32> = vec![0];
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let space_to_free = 30000000 - (70000000 - 49192532); // size of all files, precomputed
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let mut to_delete = 70000000; // arbitrarily large
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for line in lines {
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if let Ok(command) = line {
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match command.as_str() {
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"$ cd /" => continue, // skip start
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"$ ls" => continue, // we can assume this if we're not moving between directories
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s if s.starts_with("dir ") => continue, // we'll get there when we `cd`
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"$ cd .." => {
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let f = stack.pop().unwrap();
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if f > space_to_free && f < to_delete {
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to_delete = f
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}
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let last_on_stack = stack.len() - 1;
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stack[last_on_stack] += f;
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}
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s if s.starts_with("$ cd ") => {
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stack.push(0);
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}
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s => {
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// otherwise it must be a file
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let mut sp = s.split(" ");
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let last_on_stack = stack.len() - 1;
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stack[last_on_stack] += sp.next().unwrap().parse::<u32>().unwrap();
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}
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};
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}
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}
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println!("{:?}", to_delete);
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}
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}
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