Added 2022, first few problems

3 files changed, 155 insertions, 0 deletions

diff --git a/2022/07/a.rs b/2022/07/a.rs
new file mode 100644
index 0000000..a0d9a1a
--- /dev/null
+++ b/2022/07/a.rs
@@ -0,0 +1,12 @@
+mod common;
+use common::*;
+
+fn main() {
+    let fs = FileSystem::build_from_stdin();
+    let sum: usize = fs.iter()
+        .filter(|f| matches!(f.kind, FileType::Directory(_)))
+        .map(|f| f.real_size(&fs))
+        .filter(|s| *s <= 100000)
+        .sum();
+    println!("{sum}");
+}
diff --git a/2022/07/b.rs b/2022/07/b.rs
new file mode 100644
index 0000000..92bedc7
--- /dev/null
+++ b/2022/07/b.rs
@@ -0,0 +1,13 @@
+mod common;
+use common::*;
+
+fn main() {
+    let fs = FileSystem::build_from_stdin();
+    let remaining = 70000000 - fs[0].real_size(&fs);
+    let ds: usize = fs.iter()
+        .filter(|f| matches!(f.kind, FileType::Directory(_)))
+        .map(|f| f.real_size(&fs))
+        .filter(|s| *s + remaining >= 30000000)
+        .min().unwrap();
+    println!("{ds}");
+}
diff --git a/2022/07/common.rs b/2022/07/common.rs
new file mode 100644
index 0000000..675bf29
--- /dev/null
+++ b/2022/07/common.rs
@@ -0,0 +1,130 @@
+use std::ops;
+
+pub enum FileType {
+    File(usize),
+    Directory(Vec<usize>)
+}
+
+pub struct File {
+    pub kind: FileType,
+    name: String
+}
+
+impl File {
+    pub fn real_size(&self, fs: &FileSystem) -> usize {
+        match &self.kind {
+            FileType::File(s) => *s,
+            FileType::Directory(c) =>
+                c.iter().map(|x: &usize| fs[*x].real_size(&fs)).sum()
+        }
+    }
+}
+
+pub struct FileSystem {
+    files: Vec<File>
+}
+
+impl FileSystem {
+    fn new() -> Self {
+        Self {
+            files: vec![File {
+                kind: FileType::Directory(Vec::<usize>::new()),
+                name: String::from("/")
+            }]
+        }
+    }
+
+    pub fn build_from_stdin() -> Self {
+        let mut fs = FileSystem::new();
+        let mut path = Path::new();
+        let mut line = String::new();
+        while std::io::stdin().read_line(&mut line).unwrap() > 0 {
+            if &line[..5] == "$ cd " {
+                exec_cd(&line[5..], &mut path, &fs);
+            } else if &line[..3] == "dir" {
+                fs.add_dir(&line[4..line.len()-1], path.last());
+            } else if line.as_bytes()[0] != '$' as u8 {
+                let i = line.find(' ').unwrap();
+                let size = line[0..i].parse::<usize>().unwrap();
+                fs.add_file(&line[i+1..line.len()-1], size, path.last());
+            }
+            line.clear();
+        }
+        fs
+    }
+
+    fn make_parent(&mut self, id: usize, parent: usize) {
+        let p = &mut self.files[parent];
+        if let FileType::Directory(v) = &mut p.kind {
+            v.push(id);
+        } else {
+            panic!("Parent is not a directory");
+        }
+    }
+
+    fn add_dir(&mut self, name: &str, parent: usize) {
+        let id = self.files.len();
+        self.files.push(
+            File {
+                kind: FileType::Directory(Vec::<usize>::new()),
+                name: String::from(name)
+            }
+        );
+        self.make_parent(id, parent);
+    }
+
+    fn add_file(&mut self, name: &str, size: usize, parent: usize) {
+        let id = self.files.len();
+        self.files.push(
+            File {
+                kind: FileType::File(size),
+                name: String::from(name)
+            }
+        );
+        self.make_parent(id, parent);
+    }
+
+    pub fn iter(&self) -> impl Iterator<Item = &File>{
+        self.files.iter()
+    }
+}
+
+impl ops::Index<usize> for FileSystem {
+    type Output = File;
+    fn index(&self, i: usize) -> &File {
+        &self.files[i]
+    }
+}
+
+struct Path {
+    stack: Vec<usize>
+}
+
+impl Path {
+    fn new() -> Self { Self { stack: vec![0] } } // 0 is the id of "/"
+    fn last(&self) -> usize { *self.stack.last().unwrap() }
+    fn clear(&mut self) { self.stack.drain(1..); }
+    fn pop(&mut self) { self.stack.pop(); }
+    fn push(&mut self, dir_id: usize) { self.stack.push(dir_id); }
+}
+
+fn exec_cd(line: &str, path: &mut Path, fs: &FileSystem) {
+    if line.as_bytes()[0] == '/' as u8 {
+        path.clear();
+    } else if &line[..2] == ".." {
+        path.pop();
+    } else {
+        let current_dir = &fs[path.last()];
+        if let FileType::Directory(children) = &current_dir.kind {
+            for c in children {
+                if fs[*c].name == &line[..line.len()-1] {
+                    path.push(*c);
+                    return;
+                }
+            }
+        } else {
+            panic!("Non-directory in path");
+        }
+        panic!("Directory not found in current path");
+    }
+}