1 files changed, 122 insertions, 0 deletions
diff --git a/aoc22/day7/src/main.rs b/aoc22/day7/src/main.rs
new file mode 100644
index 0000000..09dbd8a
--- /dev/null
+++ b/aoc22/day7/src/main.rs
@@ -0,0 +1,122 @@
+use std::collections::HashMap;
+
+fn main() {
+    let input = lib::read_input(7);
+
+    part1(&input);
+    part2(&input);
+}
+
+fn part1(input: &str) {
+    let fs = parse(input);
+
+    let ans: u32 = fs
+        .iter()
+        .enumerate()
+        .filter(|(_, f)| matches!(f, Node::Dir { .. }))
+        .map(|(i, _)| get_size(&fs, i))
+        .filter(|&s| s <= 100_000)
+        .sum();
+
+    println!("{}", ans);
+}
+
+fn part2(input: &str) {
+    let fs = parse(input);
+
+    let used = get_size(&fs, 0);
+    let free = 70_000_000 - used;
+    let to_free = 30_000_000 - free;
+
+    let ans = fs
+        .iter()
+        .enumerate()
+        .flat_map(|(i, f)| match f {
+            Node::Dir { .. } => Some(get_size(&fs, i)),
+            _ => None,
+        })
+        .filter(|&s| s >= to_free)
+        .min_by_key(|&s| s)
+        .unwrap();
+
+    println!("{:?}", ans);
+}
+
+fn get_size<'a>(fs: &Vec<Node<'a>>, index: usize) -> u32 {
+    match &fs[index] {
+        Node::Dir { contents, .. } => contents.values().map(|&i| get_size(fs, i)).sum::<u32>(),
+        &Node::File { size, .. } => size,
+    }
+}
+
+#[derive(Debug)]
+enum Node<'a> {
+    Dir {
+        parent: usize,
+        contents: HashMap<&'a str, usize>,
+        name: &'a str,
+    },
+    File {
+        size: u32,
+        name: &'a str,
+    },
+}
+
+impl<'a> Node<'a> {
+    fn parent(&self) -> usize {
+        match self {
+            Node::Dir { parent, .. } => *parent,
+            Node::File { .. } => panic!("File has no parent"),
+        }
+    }
+    fn contents(&mut self) -> &mut HashMap<&'a str, usize> {
+        match self {
+            Node::Dir { contents, .. } => contents,
+            Node::File { .. } => panic!("File has no contents"),
+        }
+    }
+}
+
+fn parse<'a>(input: &'a str) -> Vec<Node<'a>> {
+    let mut dirs = vec![Node::Dir {
+        parent: 0,
+        contents: HashMap::new(),
+        name: "/",
+    }];
+    let mut curr = 0;
+    for line in input.lines() {
+        let s = line.split_whitespace().collect::<Vec<_>>();
+        if s[0] == "$" {
+            match s[1] {
+                "cd" => {
+                    if s[2] == "/" {
+                        curr = 0;
+                    } else if s[2] == ".." {
+                        curr = dirs[curr].parent();
+                    } else {
+                        curr = dirs[curr].contents()[s[2]];
+                    }
+                }
+                _ => {}
+            }
+        } else if s[0] == "dir" {
+            let name = s[1];
+            let node = Node::Dir {
+                parent: curr,
+                contents: HashMap::new(),
+                name,
+            };
+            let idx = dirs.len();
+            dirs.push(node);
+            dirs[curr].contents().insert(name, idx);
+        } else {
+            let size = s[0].parse().unwrap();
+            let name = s[1];
+            let node = Node::File { size, name };
+            let idx = dirs.len();
+            dirs.push(node);
+            dirs[curr].contents().insert(name, idx);
+        }
+    }
+    dirs
+}