Second star.

Too lazy to figure out proper cloning of the Dock so we just parse it twice, whatever

src/bin/p05.rs

@@ -50,27 +50,58 @@ impl FromStr for CrateStack {
 #[derive(Debug)]
 struct Dock(Vec<CrateStack>);
 
+trait Crane {
+    fn run_directive(dock: &mut Dock, directive: &MoveDirective) -> bool;
+}
+
 impl Dock {
-    fn perform_directive(&mut self, directive: &MoveDirective) -> bool {
+    fn tops(&self) -> impl Iterator<Item = Option<&Crate>> {
-        if directive.source >= self.0.len() {
+        self.0.iter().map(|s| s.0.iter().last())
+    }
+}
+
+struct CrateMover9000;
+
+impl Crane for CrateMover9000 {
+    fn run_directive(dock: &mut Dock, directive: &MoveDirective) -> bool {
+        if directive.source >= dock.0.len() {
             return false;
         }
 
-        if directive.dest >= self.0.len() {
+        if directive.dest >= dock.0.len() {
             return false;
         }
 
         for _ in 0..directive.number {
-            if let Some(s) = self.0[directive.source].pop() {
+            if let Some(s) = dock.0[directive.source].pop() {
-                self.0[directive.dest].push(s)
+                dock.0[directive.dest].push(s)
             }
         }
 
         true
     }
+}
 
-    fn tops(&self) -> impl Iterator<Item = Option<&Crate>> {
+struct CrateMover9001;
-        self.0.iter().map(|s| s.0.iter().last())
+
+impl Crane for CrateMover9001 {
+    fn run_directive(dock: &mut Dock, directive: &MoveDirective) -> bool {
+        if directive.source >= dock.0.len() {
+            return false;
+        }
+
+        if directive.dest >= dock.0.len() {
+            return false;
+        }
+
+        let source_vec = &mut dock.0[directive.source].0;
+
+        let drained: Vec<Crate> = source_vec
+            .drain((source_vec.len() - usize::try_from(directive.number).unwrap())..)
+            .collect();
+        dock.0[directive.dest].0.extend(drained);
+
+        true
     }
 }
 
@@ -158,20 +189,29 @@ fn main() {
     println!("PART ONE ---------------");
     part1(dock, &moves);
 
+    let dock2: Dock = string
+        .split("\n\n")
+        .next()
+        .expect("first section")
+        .parse::<Dock>()
+        .expect("can't parse dock");
+
     println!("\n PART TWO ---------------");
+    part2(dock2, &moves);
 }
 
 fn part1(mut dock: Dock, moves: &[MoveDirective]) {
     for m in moves {
-        dock.perform_directive(m);
+        CrateMover9000::run_directive(&mut dock, m);
     }
 
     dbg!(dock.tops().flatten().map(|c| c.0).collect::<String>());
 }
 
-fn part2() {}
+fn part2(mut dock: Dock, moves: &[MoveDirective]) {
+    for m in moves {
+        CrateMover9001::run_directive(&mut dock, m);
+    }
 
-#[cfg(test)]
+    dbg!(dock.tops().flatten().map(|c| c.0).collect::<String>());
-mod tests {
-    use super::*;
 }