2022 day5/rust: cleanup

2022/day5/rust/src/main.rs

@@ -18,14 +18,10 @@ fn main() {
             break;
         }
 
-        for (i, crate_) in line.as_bytes().chunks(4).enumerate() {
+        let crates = line.as_bytes().chunks(4).map(|crate_| {
-            if stacks.len() <= i {
-                stacks.push(vec![]);
-            }
-
             if crate_.iter().all(|&c| c == b' ') {
                 // empty space
-                continue;
+                return None;
             }
 
             let crate_ = crate_.strip_suffix(b" ").unwrap_or(crate_);
@@ -37,20 +33,43 @@ fn main() {
                 panic!("invalid crate {:?} {}", crate_, std::str::from_utf8(crate_).unwrap());
             };
 
-            stacks[i].push(*crate_ as char);
+            Some(*crate_ as char)
-        }
+        });
+
+        for (i, crate_) in crates.enumerate() {
+            if stacks.len() <= i {
+                stacks.push(vec![]);
             }
 
+            if let Some(crate_) = crate_ {
+                stacks[i].push(crate_);
+            }
+        }
+    }
     for stack in &mut stacks {
         stack.reverse();
     }
-
     let stacks = stacks;
+
     let mut stacks_9000 = stacks.clone();
     let mut stacks_9001 = stacks;
 
     let regex = Regex::new(r"move (\d+) from (\d+) to (\d+)").unwrap();
     for line in lines {
+        fn get_stacks(
+            stacks: &mut [Vec<char>],
+            source: usize,
+            dest: usize,
+        ) -> (&mut Vec<char>, &mut Vec<char>) {
+            let (p1, p2) = stacks.split_at_mut(usize::max(source, dest));
+
+            if source < dest {
+                (&mut p1[source], &mut p2[0])
+            } else {
+                (&mut p2[0], &mut p1[dest])
+            }
+        }
+
         let matches = regex.captures(line).unwrap();
 
         let amount: usize = matches[1].parse().unwrap();
@@ -61,14 +80,7 @@ fn main() {
         let dest = dest - 1;
 
         {
-            let (p1, p2) = stacks_9000.split_at_mut(usize::max(source, dest));
+            let (source, dest) = get_stacks(&mut stacks_9000, source, dest);
-
-            let (source, dest) = if source < dest {
-                (&mut p1[source], &mut p2[0])
-            } else {
-                (&mut p2[0], &mut p1[dest])
-            };
-
             let sourceidx = source.len() - amount;
 
             dest.extend(source[sourceidx..].iter().copied().rev());
@@ -76,14 +88,7 @@ fn main() {
         }
 
         {
-            let (p1, p2) = stacks_9001.split_at_mut(usize::max(source, dest));
+            let (source, dest) = get_stacks(&mut stacks_9001, source, dest);
-
-            let (source, dest) = if source < dest {
-                (&mut p1[source], &mut p2[0])
-            } else {
-                (&mut p2[0], &mut p1[dest])
-            };
-
             let sourceidx = source.len() - amount;
 
             dest.extend(source[sourceidx..].iter().copied());
@@ -91,19 +96,10 @@ fn main() {
         }
     }
 
+    for stacks in [stacks_9000, stacks_9001] {
         println!(
             "{}",
-        stacks_9000
+            stacks.iter().map(|s| s.last().unwrap()).collect::<String>()
-            .iter()
-            .map(|s| s.last().unwrap())
-            .collect::<String>()
-    );
-
-    println!(
-        "{}",
-        stacks_9001
-            .iter()
-            .map(|s| s.last().unwrap())
-            .collect::<String>()
         );
     }
+}