Day 7 done... forgot to commit last night

2022/rust/src/day7.rs

@@ -1,107 +1,61 @@
 mod common;
 
-use std::cell::RefCell;
-use std::collections::HashMap;
-use std::collections::HashSet;
-use std::rc::Rc;
+use std::{collections::HashMap, num::Wrapping};
 
-#[derive(Debug, Clone)]
-struct DirTree {
-    files: HashMap<String, usize>,
-    subdirectories: HashMap<String, Rc<RefCell<Self>>>,
-    parent: Option<Rc<RefCell<Self>>>,
-}
-
-impl DirTree {
-    pub fn new(parent: Option<Rc<RefCell<Self>>>) -> Self {
-        Self {
-            files: HashMap::new(),
-            subdirectories: HashMap::new(),
-            parent,
-        }
-    }
-
-    pub fn root() -> Self {
-        Self::new(None)
-    }
-}
-
-type Input = Rc<RefCell<DirTree>>;
-type Result = usize;
+type Result = Wrapping<usize>;
+type Input = HashMap<String, Result>;
 
 fn processed_input(input: &str) -> Input {
-    let root = Rc::new(RefCell::new(DirTree::root()));
-    let mut current_dir = Rc::clone(&root);
+    let mut result: Input = HashMap::from([("/".to_string(), Wrapping(0))]);
+    let mut current_path = vec![];
+
+    let vp = |v: &[&str]| format!("/{}", v.join("/"));
 
     for l in input.lines() {
         println!("line: {}", l);
         if l == "$ cd /" {
-            current_dir = Rc::clone(&root);
+            println!("cwd '/'");
+            current_path.clear();
         } else if l == "$ ls" {
             continue;
         } else if l.starts_with("dir ") {
-            let d = &l[4..];
-            current_dir.borrow_mut().subdirectories.insert(
-                d.to_string(),
-                Rc::new(RefCell::new(DirTree::new(Some(Rc::clone(&current_dir))))),
-            );
+            current_path.push(&l[4..]);
+            let p = vp(&current_path);
+            println!("inserting path '{}'", p);
+            current_path.pop();
+            result.insert(p, Wrapping(0));
         } else if l.starts_with("$ cd ..") {
-            let cur = Rc::clone(&current_dir);
-            current_dir = Rc::clone(&cur.borrow().parent.as_ref().unwrap());
+            current_path.pop();
+            println!("cwd '{}'", vp(&current_path));
         } else if l.starts_with("$ cd ") {
-            let d = &l[5..];
-            let cur = Rc::clone(&current_dir);
-            current_dir = Rc::clone(&cur.borrow().subdirectories.get(d).unwrap());
+            current_path.push(&l[5..]);
+            println!("cwd '{}'", vp(&current_path));
         } else {
-            let mut args = l.split(' ');
-            let size = args.next().unwrap().parse::<usize>().unwrap();
-            current_dir
-                .borrow_mut()
-                .files
-                .insert(args.next().unwrap().to_string(), size);
+            let size = l.split(' ').next().unwrap().parse::<usize>().unwrap();
+            for i in (0..=current_path.len()).rev() {
+                let p = vp(&current_path[0..i]);
+                println!("adding {} to path '{}'", size, p);
+                *(result.get_mut(&p).unwrap()) += size;
+            }
         }
     }
-    return root;
+
+    return result;
 }
 
 const PART1_LIMIT: usize = 100_000;
 
-fn dfs1(input: Input, path: String) -> usize {
-    let dt = input.borrow();
-
-    let files_size = dt.files.values().map(|r| r.to_owned()).sum::<usize>();
-    let subdir_sizes: Vec<usize> = dt
-        .subdirectories
-        .iter()
-        .map(|(p, sdt)| dfs1(sdt.clone(), format!("{}/{}", path, p)))
-        .collect();
-    let subdirs_size = subdir_sizes.iter().sum::<usize>();
-    let this_dir_size = subdirs_size + files_size;
-
-    let counted = subdir_sizes.iter().filter(|s| **s < PART1_LIMIT).sum();
-
-    println!(
-        "path: {}, files: {:?}, files_size: {}, subdirs_size: {}, counted: {}",
-        path, dt.files, files_size, subdirs_size, counted
-    );
-    let mut r = counted;
-    if this_dir_size < PART1_LIMIT {
-        r = counted + this_dir_size;
-    }
-    println!(
-        "return {}, {}",
-        counted + this_dir_size,
-        "hy" // std::backtrace::Backtrace::capture()
-    );
-    return r;
-}
-
 fn part1(input: &Input) -> Result {
-    dfs1(input.clone(), "".to_string())
+    let lim = Wrapping(PART1_LIMIT);
+    input.values().filter(|s| **s < lim).sum()
 }
 
 fn part2(input: &Input) -> Result {
-    0
+    let to_free = input.get("/").unwrap() - Wrapping(40_000_000);
+    *input
+        .values()
+        .min_by(|a, b| (**a - to_free).cmp(&(**b - to_free)))
+        .unwrap()
 }
 
 fn main() {
@@ -109,13 +63,8 @@ fn main() {
     eprintln!("{}\n\nAbove is your input file.\n\n", input_text);
     let input = processed_input(&input_text);
     common::show_answers(&part1(&input), &part2(&input))
-    // common::show_both_answers(&both_parts(&input))
 }
 
-// fn both_parts(input: &Input) -> (Result, Result) {
-//     (0, 0)
-// }
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -147,52 +96,7 @@ $ ls
     #[test]
     fn test() {
         let input = processed_input(TEST_INPUT);
-        assert_eq!(part1(&input), 95437);
-        assert_eq!(part2(&input), 0);
-        // assert_eq!(both_parts(&input), (0, 0));
-    }
-
-    const TEST_INPUT2: &str = "$ cd /
-$ ls
-dir a
-100 x.txt
-$ cd a
-$ ls
-dir b
-100 y.txt
-$ cd b
-$ ls
-100 z.txt";
-    const TEST_INPUT3: &str = "$ cd /
-$ ls
-dir a
-100 x.txt
-$ cd a
-$ ls
-dir b
-100 y.txt
-$ cd b
-$ ls
-dir c
-100 z.txt
-$ cd c
-$ ls
-100 zz.txt";
-    // $ cd a
-    // $ ls
-    // dir a
-    // 100 c.txt
-    // $ cd a
-    // $ ls
-    // 100 d.txt
-    // ";
-
-    #[test]
-    fn test2() {
-        let input = processed_input(TEST_INPUT2);
-        assert_eq!(part1(&input), 600);
-        let input3 = processed_input(TEST_INPUT2);
-        assert_eq!(part1(&input), 1000);
-        // assert_eq!(both_parts(&input), (0, 0));
+        assert_eq!(part1(&input), Wrapping(95437));
+        assert_eq!(part2(&input), Wrapping(24933642));
     }
 }