day 7 solution

2022/src/days/day7.rs

@@ -0,0 +1,177 @@
+use anyhow::{anyhow, Result};
+use std::fs;
+use std::collections::BTreeMap;
+
+#[derive(Debug,Default)]
+struct Dir {
+    name: String,
+    files: Vec<File>,
+    directories: Vec<Dir>,
+    total_size: usize,
+}
+
+#[derive(Debug)]
+struct File {
+    name: String,
+    size: usize,
+}
+
+fn dig_directory<'a, 'b>(dirname: &'b String, fs: &'a mut Dir) -> Option<&'a mut Dir> {
+    if dirname == "/" && fs.name == *dirname {
+        return Some(fs);
+    }
+    for entry in fs.directories.iter_mut() {
+        if entry.name == *dirname {
+            return Some(entry);
+        } else if dirname.starts_with(&entry.name) {
+            return dig_directory(dirname, entry);
+        }
+    }
+
+    None
+}
+
+fn just_sizes<'a>(dir: &'a mut Dir) -> usize {
+    let mut size: usize = 0;
+
+    for file in dir.files.iter() {
+        size += file.size;
+    }
+
+    for subdir in dir.directories.iter_mut() {
+        size += just_sizes(subdir);
+    }
+
+    dir.total_size = size;
+    size
+}
+
+fn part_one_sizes<'a>(dir: &'a Dir) -> usize {
+    let mut size: usize = 0;
+
+    if dir.total_size > 100000 {
+        size = 0
+    } else {
+        size += dir.total_size;
+    }
+
+    for subdir in dir.directories.iter() {
+        size += part_one_sizes(subdir);
+    }
+
+    size
+}
+
+fn part_two_sizes<'a>(dir: &'a Dir, needed: u32) -> Option<(u32, &'a str)> {
+    let mut map: BTreeMap<u32, &'a str> = BTreeMap::new();
+    part_two_recurse(&mut map, dir);
+
+    for (key, val) in map.iter() {
+        if *key >= needed {
+            return Some((*key, val))
+        }
+    }
+
+    None
+}
+
+fn part_two_recurse<'a>(map: &mut BTreeMap<u32, &'a str>, dir: &'a Dir) {
+    map.insert((dir.total_size as u32).try_into().unwrap(), dir.name.as_str());
+    for subdir in dir.directories.iter() {
+        part_two_recurse(map, subdir);
+    }
+}
+
+pub fn run() -> Result<()> {
+    let file_contents = fs::read_to_string("day7.txt")?;
+    //let file_contents = fs::read_to_string("tests/day7.txt")?;
+
+    let mut root = Dir {
+        name: String::from("/"),
+        ..Default::default()
+    };
+    let mut current_path: Vec<&str> = Vec::with_capacity(25);
+    let mut current = &mut root;
+
+    for line in file_contents.lines() {
+        if &line[0..1] == "$" {
+            let cmd = &line[2..4];
+            match cmd {
+                "ls" => {
+                    continue;
+                }
+                "cd" => {
+                    let dirname = &line[5..];
+                    current = &mut root;
+                    if dirname == ".." {
+                        current_path.pop().expect("going past root");
+                        let newdir = format!("/{}", current_path.join("/"));
+                        current = dig_directory(&newdir, current).expect("missing .. dir");
+                    } else if dirname == "/" {
+                        current_path.clear();
+                    } else {
+                        current_path.push(dirname);
+                        let newdir = format!("/{}", current_path.join("/"));
+                        current = dig_directory(&newdir, current).expect("missing subdir");
+                    }
+                    continue;
+                }
+                _ => {
+                    return Err(anyhow!("unknown command {}", line));
+                }
+            }
+        } else if line.chars().next().unwrap().is_numeric() {
+            let mut fields = line.split_whitespace();
+            let size: usize = fields
+                .next()
+                .expect("missing file size")
+                .parse()
+                .expect("invalid file size");
+            let name = fields.next().expect("missing file name");
+
+            current_path.push(name);
+            let new_filename = format!("/{}", current_path.join("/"));
+            current_path.pop();
+
+            if let None = current.files.iter().find(|x| x.name == new_filename) {
+                current.files.push(File {
+                    name: new_filename,
+                    size: size,
+                });
+            }
+        } else if line.starts_with("dir") {
+            let current_dirname = &line[4..];
+
+            current_path.push(current_dirname);
+            let new_dirname = format!("/{}", current_path.join("/"));
+            current_path.pop();
+
+            if let None = current.directories.iter().find(|x| x.name == new_dirname) {
+                let dir = Dir {
+                    name: new_dirname,
+                    ..Default::default()
+                };
+                current.directories.push(dir);
+            }
+        } else {
+            return Err(anyhow!("malformed line {}", line));
+        }
+    }
+
+    just_sizes(&mut root);
+    println!("part one {}", part_one_sizes(&root));
+
+    let total_disk = 70000000;
+    let min_free_space = 30000000;
+    let free_space = total_disk - root.total_size as u32;
+    let needed_space = min_free_space - free_space;
+    println!("total size used {} free {} needed {}", root.total_size, free_space, needed_space);
+
+    if let Some((rm_space, rm_name)) = part_two_sizes(&root, needed_space) {
+        println!("part two: should delete {} to reclaim {} total free space {}", rm_name, rm_space, free_space + rm_space);
+    } else {
+        println!("could not find part 2");
+    }
+
+    Ok(())
+}

2022/src/days/mod.rs

@@ -4,3 +4,4 @@ pub mod day3;
 pub mod day4;
 pub mod day5;
 pub mod day6;
+pub mod day7;

2022/src/main.rs

@@ -4,7 +4,10 @@ use std::env;
 mod days;
 
 fn help() {
-    println!("Usage: {} <day-number>", env!("CARGO_BIN_NAME"));
+    println!(
+        "Usage: {} day-number <day-number>...",
+        env!("CARGO_BIN_NAME")
+    );
 }
 
 fn run_day(number: i32) -> Result<()> {
@@ -27,6 +30,9 @@ fn run_day(number: i32) -> Result<()> {
         6 => {
             days::day6::run()?;
         }
+        7 => {
+            days::day7::run()?;
+        }
         _ => return Err(anyhow!("Invalid day provided")),
     }
     Ok(())
@@ -36,19 +42,27 @@ fn main() -> Result<()> {
     let args: Vec<String> = env::args().collect();
 
     match args.len() {
-        2 => {
-            let number: i32 = match args[1].parse() {
-                Ok(n) => n,
-                Err(_) => {
-                    help();
-                    return Err(anyhow!("Argument is not an integer"));
-                }
-            };
-            run_day(number)?;
+        0 => {
+            help();
+            return Err(anyhow!("No arguments provided"));
+        }
+        1 => {
+            help();
+            return Err(anyhow!("Not enough arguments provided"));
         }
         _ => {
-            help();
-            return Err(anyhow!("Invalid arguments provided"));
+            for val in args[1..].iter() {
+                let number: i32 = match val.parse() {
+                    Ok(n) => n,
+                    Err(_) => {
+                        help();
+                        return Err(anyhow!("Argument {} is not an integer", val));
+                    }
+                };
+                println!("Day {}", number);
+                run_day(number)?;
+                println!("");
+            }
         }
     }
 

2022/tests/day7.txt

@@ -0,0 +1,23 @@
+$ 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