Day 5, puzzle 2

src/bin/d5p2.rs

@@ -0,0 +1,34 @@
+use std::collections::VecDeque;
+
+use aoc22::{day5, util};
+
+pub fn main() {
+    let mut arrangement = day5::parse_arrangement(&util::parse_input());
+
+    for inst in &arrangement.instructions {
+        let mut boxes = VecDeque::new();
+        for _ in 0..inst.num {
+            let box_ = arrangement
+                .stacks
+                .get_mut(inst.from)
+                .unwrap()
+                .pop_back()
+                .unwrap();
+            boxes.push_front(box_);
+        }
+
+        arrangement
+            .stacks
+            .get_mut(inst.to)
+            .unwrap()
+            .append(&mut boxes);
+    }
+
+    let top_boxes: String = arrangement
+        .stacks
+        .iter()
+        .map(|s| s.iter().next_back().unwrap())
+        .collect();
+
+    println!("The top boxes are {}", top_boxes);
+}