diff --git a/src/main.rs b/src/main.rs
index fc41c56..7ae8744 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,11 +1,11 @@
 use palette::{IntoColor, OklabHue, Oklch, Srgb};
 use std::{
-    collections::{BinaryHeap, HashMap, HashSet, VecDeque},
+    collections::{BinaryHeap, HashMap, HashSet},
     fmt::Display,
     hash::{DefaultHasher, Hash, Hasher},
     io::{self, Write, stdin, stdout},
     iter,
-    num::{self, NonZero},
+    num::NonZero,
     ops::ControlFlow,
 };
 
@@ -60,12 +60,6 @@ pub struct Tower<const TOWER_HEIGHT: usize = 4> {
     pub rings: [Option<Ring>; TOWER_HEIGHT],
 }
 
-macro_rules! tower {
-    ($($rings: literal),*) => {
-        Tower::new(&[$(Ring(std::num::NonZero::new($rings).unwrap())),*])
-    };
-}
-
 impl<const TOWER_HEIGHT: usize> Tower<TOWER_HEIGHT> {
     const EMPTY: Self = Self {
         rings: [None; TOWER_HEIGHT],
@@ -74,7 +68,7 @@ impl<const TOWER_HEIGHT: usize> Tower<TOWER_HEIGHT> {
     pub fn new(rings: &[Ring]) -> Self {
         let mut tower = Self::EMPTY;
 
-        for (src, dst) in rings.into_iter().zip(&mut tower.rings) {
+        for (src, dst) in rings.iter().zip(&mut tower.rings) {
             *dst = Some(*src);
         }
 
@@ -87,22 +81,19 @@ impl<const TOWER_HEIGHT: usize> Tower<TOWER_HEIGHT> {
         let mut max_same_ring_type_score = 0;
         let mut burried_score = 0;
 
-        for i in self.rings.iter().rev() {
-            if let Some(ring) = i {
-                if let Some(existing_ring_type) = ring_type {
-                    if existing_ring_type == *ring {
-                        same_ring_type_score += 2;
-                    } else {
-                        max_same_ring_type_score =
-                            max_same_ring_type_score.max(same_ring_type_score);
-                        burried_score += 2usize.pow(max_same_ring_type_score);
-                        same_ring_type_score = 0;
-                        ring_type = Some(*ring);
-                    }
+        for ring in self.rings.iter().rev().flatten() {
+            if let Some(existing_ring_type) = ring_type {
+                if existing_ring_type == *ring {
+                    same_ring_type_score += 2;
                 } else {
+                    max_same_ring_type_score = max_same_ring_type_score.max(same_ring_type_score);
+                    burried_score += 2usize.pow(max_same_ring_type_score);
                     same_ring_type_score = 0;
                     ring_type = Some(*ring);
                 }
+            } else {
+                same_ring_type_score = 0;
+                ring_type = Some(*ring);
             }
         }
 
@@ -206,18 +197,16 @@ impl<const TOWER_HEIGHT: usize> Tower<TOWER_HEIGHT> {
         let mut ring_type = None;
         let mut count = 0;
 
-        for i in &self.rings {
-            if let Some(ring) = i {
-                if let Some(existing_ring_type) = ring_type {
-                    if existing_ring_type == *ring {
-                        count += 1;
-                    } else {
-                        return None;
-                    }
+        for ring in self.rings.iter().flatten() {
+            if let Some(existing_ring_type) = ring_type {
+                if existing_ring_type == *ring {
+                    count += 1;
                 } else {
-                    count = 1;
-                    ring_type = Some(*ring);
+                    return None;
                 }
+            } else {
+                count = 1;
+                ring_type = Some(*ring);
             }
         }
 
@@ -256,14 +245,12 @@ impl<const TOWER_HEIGHT: usize> Game<TOWER_HEIGHT> {
         let mut ring_sets = HashMap::new();
         for t in &towers {
             t.check();
-            for r in &t.rings {
-                if let Some(r) = r {
-                    *ring_sets.entry(*r).or_insert(0) += 1;
-                }
+            for r in t.rings.iter().flatten() {
+                *ring_sets.entry(*r).or_insert(0) += 1;
             }
         }
 
-        for (ring, _num) in &ring_sets {
+        for ring in ring_sets.keys() {
             // ok as long as the goal isn't sets of 4 but single-ringtype towers
             // if num != TOWER_HEIGHT {
             // panic!("incomplete ring set: expected {TOWER_HEIGHT} of {ring} but found {num}");
@@ -332,9 +319,14 @@ impl<const TOWER_HEIGHT: usize> Game<TOWER_HEIGHT> {
             hasher.finish()
         };
 
-        #[derive(PartialEq, PartialOrd)]
+        #[derive(PartialEq)]
         struct Ordf32(f32);
         impl Eq for Ordf32 {}
+        impl PartialOrd for Ordf32 {
+            fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+                Some(self.cmp(other))
+            }
+        }
         impl Ord for Ordf32 {
             fn cmp(&self, other: &Self) -> std::cmp::Ordering {
                 self.0.total_cmp(&other.0)
@@ -749,6 +741,12 @@ impl<const TOWER_HEIGHT: usize> UndoStack<TOWER_HEIGHT> {
     }
 }
 
+impl<const TOWER_HEIGHT: usize> Default for UndoStack<TOWER_HEIGHT> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 fn main() -> io::Result<()> {
     let mut g = GameGenerator {
         num_extra_towers: 2,
@@ -784,6 +782,12 @@ fn main() -> io::Result<()> {
 mod tests {
     use crate::{Game, Move, Ring, Tower};
 
+    macro_rules! tower {
+        ($($rings: literal),*) => {
+            Tower::new(&[$(Ring(std::num::NonZero::new($rings).unwrap())),*])
+        };
+    }
+
     #[test]
     fn test_moves() {
         let mut g = Game::<4>::new(vec![tower![1, 2, 1, 2], Tower::EMPTY, Tower::EMPTY]);