2022-7...

src/bin/2022-7.rs

@@ -0,0 +1,169 @@
+use eyes::parse;
+use itertools::Itertools;
+use std::{cell::RefCell, collections::HashMap, iter, rc::Rc};
+
+fn main() {
+    let input = aoc::input!();
+    println!("part 1: {}", part1(&input));
+    println!("part 1: {}", part2(&input));
+}
+
+type RefNode = Rc<RefCell<Node>>;
+#[derive(Default)]
+struct Node {
+    size: u64,
+    children: HashMap<String, RefNode>,
+    parent: Option<RefNode>,
+}
+
+impl Node {
+    fn total_size(&self) -> u64 {
+        self.children
+            .values()
+            .map(|child| child.borrow().total_size())
+            .sum::<u64>()
+            + self.size
+    }
+}
+
+fn all_dirs(n: RefNode) -> Box<dyn Iterator<Item = RefNode>> {
+    let children = n.borrow().children.values().cloned().collect::<Vec<_>>();
+
+    Box::new(
+        iter::once(n).chain(
+            children
+                .into_iter()
+                .filter_map(|c| {
+                    if c.borrow().size == 0 {
+                        Some(all_dirs(c))
+                    } else {
+                        None
+                    }
+                })
+                .flatten(),
+        ),
+    )
+}
+
+fn part1(input: &str) -> u64 {
+    let root = RefNode::default();
+    let mut node = root.clone();
+
+    for line in input.lines() {
+        match line {
+            l if l.starts_with("$ cd") => {
+                let dir = parse!(l, "$ cd {}", String);
+                match dir.as_str() {
+                    "/" => continue,
+                    ".." => {
+                        let parent = node.borrow().parent.clone().unwrap();
+                        node = parent;
+                    }
+                    _ => {
+                        let child = node.borrow_mut().children.entry(dir).or_default().clone();
+                        node = child;
+                    }
+                }
+            } // cd
+            l if l.starts_with("$ ls") => continue, // ls
+            l if l.starts_with("dir ") => {
+                // dir entry
+                let dir = parse!(l, "dir {}", String);
+                let entry = node.borrow_mut().children.entry(dir).or_default().clone();
+                entry.borrow_mut().parent = Some(node.clone());
+            }
+            l => {
+                // file entry
+                let (size, file) = parse!(l, "{} {}", u64, String);
+                let entry = node.borrow_mut().children.entry(file).or_default().clone();
+                entry.borrow_mut().size = size;
+                entry.borrow_mut().parent = Some(node.clone());
+            }
+        }
+    }
+
+    all_dirs(root)
+        .map(|d| d.borrow().total_size())
+        .filter(|&s| s <= 100_000)
+        .sum::<u64>()
+}
+
+fn part2(input: &str) -> u64 {
+    let root = RefNode::default();
+    let mut node = root.clone();
+
+    for line in input.lines() {
+        match line {
+            l if l.starts_with("$ cd") => {
+                let dir = parse!(l, "$ cd {}", String);
+                match dir.as_str() {
+                    "/" => continue,
+                    ".." => {
+                        let parent = node.borrow().parent.clone().unwrap();
+                        node = parent;
+                    }
+                    _ => {
+                        let child = node.borrow_mut().children.entry(dir).or_default().clone();
+                        node = child;
+                    }
+                }
+            } // cd
+            l if l.starts_with("$ ls") => continue, // ls
+            l if l.starts_with("dir ") => {
+                // dir entry
+                let dir = parse!(l, "dir {}", String);
+                let entry = node.borrow_mut().children.entry(dir).or_default().clone();
+                entry.borrow_mut().parent = Some(node.clone());
+            }
+            l => {
+                // file entry
+                let (size, file) = parse!(l, "{} {}", u64, String);
+                let entry = node.borrow_mut().children.entry(file).or_default().clone();
+                entry.borrow_mut().size = size;
+                entry.borrow_mut().parent = Some(node.clone());
+            }
+        }
+    }
+
+    let free_space = 70000000 - root.borrow().total_size();
+    all_dirs(root)
+        .map(|d| d.borrow().total_size())
+        .filter(|&s| s >= 30000000 - free_space)
+        .min()
+        .unwrap()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn examples() {
+        let example = 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"#;
+
+        assert_eq!(part1(example), 95437);
+        assert_eq!(part2(example), 24933642);
+    }
+}