add day 7, part 1

day07/common.rs

@@ -0,0 +1,112 @@
+// Copyright 2022 Christian Ulrich
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+use std::io;
+use std::iter;
+
+#[derive(Debug)]
+pub enum Node {
+    Directory { name: String, children: Vec<Node> },
+    File { name: String, size: usize },
+}
+
+pub struct FileSystem {
+    root: Node,
+}
+
+impl Node {
+    pub fn name(&self) -> &str {
+        match self {
+            Node::File { name, size: _ } => name,
+            Node::Directory { name, children: _ } => name,
+        }
+    }
+
+    pub fn size(&self) -> usize {
+        match self {
+            Node::File { name: _, size } => *size,
+            Node::Directory { name: _, children } => {
+                children.iter().fold(0, |acc, c| acc + c.size())
+            }
+        }
+    }
+
+    pub fn walk(&self) -> Box<dyn Iterator<Item = &Node> + '_> {
+        match self {
+            Node::File { name: _, size: _ } => Box::new(iter::empty()),
+            Node::Directory { name: _, children } => Box::new(
+                children.iter().chain(
+                    children
+                        .iter()
+                        .skip(1)
+                        .fold(children[0].walk(), |acc, c| Box::new(acc.chain(c.walk()))),
+                ),
+            ),
+        }
+    }
+}
+
+impl FileSystem {
+    pub fn from_stdin() -> Result<FileSystem, &'static str> {
+        let mut line = String::new();
+        if let Ok(_) = io::stdin().read_line(&mut line) {
+            return Ok(FileSystem {
+                root: FileSystem::parse_dir(&line)?,
+            });
+        }
+        Err("input file is empty")
+    }
+
+    pub fn root(&self) -> &Node {
+        &self.root
+    }
+
+    fn parse_file(line: &str) -> Result<Node, &'static str> {
+        if let Some((size, name)) = line.trim().split_once(' ') {
+            return Ok(Node::File {
+                name: name.into(),
+                size: size.parse().map_err(|_| "failed to parse file")?,
+            });
+        }
+        Err("failed to parse file")
+    }
+
+    fn parse_dir(line: &str) -> Result<Node, &'static str> {
+        if !line.starts_with("$ cd ") {
+            return Err("cannot parse directory");
+        }
+        let name = line[5..].trim();
+        let mut children = vec![];
+        let mut line = String::new();
+        match io::stdin().read_line(&mut line) {
+            Ok(_) if { line == "$ ls\n" } => (),
+            _ => return Err("cannot parse directory"),
+        }
+        loop {
+            line.clear();
+            match io::stdin().read_line(&mut line) {
+                Ok(_) if { line.starts_with("dir ") } => (),
+                Ok(_) if { line.trim().is_empty() || line == "$ cd ..\n" } => break,
+                Ok(_) if { line.starts_with("$ cd ") } => children.push(Self::parse_dir(&line)?),
+                Ok(_) => children.push(Self::parse_file(&line)?),
+                _ => assert!(false),
+            }
+        }
+        Ok(Node::Directory {
+            name: name.into(),
+            children: children,
+        })
+    }
+}

day07/part1.rs

@@ -0,0 +1,39 @@
+// Copyright 2022 Christian Ulrich
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+// usage: ./part1 < input
+
+pub mod common;
+
+use common::{FileSystem, Node};
+
+fn main() -> Result<(), &'static str> {
+    let fs = FileSystem::from_stdin()?;
+    let mut result = 0;
+    for node in fs.root().walk() {
+        if let Node::Directory {
+            name: _,
+            children: _,
+        } = node
+        {
+            let size = node.size();
+            if size <= 100000 {
+                result += size;
+            }
+        }
+    }
+    println!("{result}");
+    Ok(())
+}

day07/testinput

@@ -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