Finish day 5

2022/src/day5.rs

@@ -16,7 +16,8 @@ pub fn part1() -> String {
 }
 
 pub fn part2() -> String {
-    unimplemented!()
+    let (stacks, commands) = input(INPUT);
+    tops(run_commands_multicrate(stacks, commands))
 }
 
 fn run_commands(stacks: Stacks<char>, commands: Vec<Command>) -> Stacks<char> {
@@ -25,6 +26,12 @@ fn run_commands(stacks: Stacks<char>, commands: Vec<Command>) -> Stacks<char> {
         .fold(stacks, |stacks, command| stacks.run_command(command))
 }
 
+fn run_commands_multicrate(stacks: Stacks<char>, commands: Vec<Command>) -> Stacks<char> {
+    commands.into_iter().fold(stacks, |stacks, command| {
+        stacks.run_command_multicrate(command)
+    })
+}
+
 fn tops(stacks: Stacks<char>) -> String {
     stacks
         .0
@@ -125,6 +132,25 @@ impl<T: Clone + Copy> Stacks<T> {
         });
         self
     }
+
+    fn run_command_multicrate(mut self, cmd: Command) -> Self {
+        let Command {
+            count,
+            source,
+            dest,
+        } = cmd;
+
+        let mut stack = Vec::new();
+        (0..count).for_each(|_| {
+            let val = self.0[(source - 1) as usize].pop().unwrap();
+            stack.push(val);
+        });
+        while stack.len() > 0 {
+            self.0[(dest - 1) as usize].push(stack.pop().unwrap());
+        }
+
+        self
+    }
 }
 
 fn input(data: &str) -> (Stacks<char>, Vec<Command>) {
@@ -263,6 +289,23 @@ move 1 from 1 to 2";
         });
     }
 
+    #[test]
+    fn it_can_follow_multicrate_commands() {
+        with_input(|(stacks, commands)| {
+            let stacks = stacks.run_command_multicrate(commands[0].clone());
+            assert_eq!(stacks.0[0].0, vec!['Z', 'N', 'D']);
+            assert_eq!(stacks.0[1].0, vec!['M', 'C']);
+            assert_eq!(stacks.0[2].0, vec!['P']);
+        });
+
+        with_input(|(stacks, commands)| {
+            let stacks = run_commands_multicrate(stacks, commands);
+            assert_eq!(stacks.0[0].0, vec!['M']);
+            assert_eq!(stacks.0[1].0, vec!['C']);
+            assert_eq!(stacks.0[2].0, vec!['P', 'Z', 'N', 'D']);
+        });
+    }
+
     #[test]
     fn it_can_find_tops() {
         with_input(|(stacks, commands)| {