diff --git a/day_07/src/equation.rs b/day_07/src/equation.rs
index 0c6914c..510b709 100644
--- a/day_07/src/equation.rs
+++ b/day_07/src/equation.rs
@@ -66,11 +66,10 @@ impl Equation {
         accumulator
     }
 
+    const MULTIPLY_ADD_SET: [Op; 2] = [Op::Add, Op::Multiply];
     pub fn solvable_multiply_add(&self) -> bool {
-        let op_combinations = create_permutations(
-            HashSet::from([Op::Add, Op::Multiply]),
-            self.components.len() - 1,
-        );
+        let op_combinations =
+            create_permutations(&Equation::MULTIPLY_ADD_SET, self.components.len() - 1);
 
         for combination in op_combinations {
             if self.answer == self.compute_answer(&combination) {
@@ -80,9 +79,10 @@ impl Equation {
         false
     }
 
+    const MULTIPLY_ADD_CONCAT_SET: [Op; 3] = [Op::Add, Op::Multiply, Op::Concat];
     pub fn solvable_multiply_add_concat(&self) -> bool {
         let op_combinations = create_permutations(
-            HashSet::from([Op::Add, Op::Multiply, Op::Concat]),
+            &Equation::MULTIPLY_ADD_CONCAT_SET,
             self.components.len() - 1,
         );
 
diff --git a/day_07/src/equation/operator_set.rs b/day_07/src/equation/operator_set.rs
index 307af72..c69c96d 100644
--- a/day_07/src/equation/operator_set.rs
+++ b/day_07/src/equation/operator_set.rs
@@ -14,11 +14,8 @@ struct PermutationCacheKey {
 }
 
 impl PermutationCacheKey {
-    fn new(size: usize, set: &HashSet<Op>) -> PermutationCacheKey {
-        PermutationCacheKey {
-            size,
-            set: set.iter().cloned().collect(),
-        }
+    fn new(size: usize, set: Vec<Op>) -> PermutationCacheKey {
+        PermutationCacheKey { size, set }
     }
 }
 
@@ -42,7 +39,7 @@ fn store_operator_set_in_cache(cache_key: PermutationCacheKey, cache_value: Hash
 }
 
 fn create_permutations_recurse(
-    values: &HashSet<Op>,
+    values: &[Op],
     len: usize,
     permutations: &mut HashSet<Vec<Op>>,
     curr_permutation: Vec<Op>,
@@ -59,13 +56,13 @@ fn create_permutations_recurse(
     }
 }
 
-pub fn create_permutations(set: HashSet<Op>, len: usize) -> HashSet<Vec<Op>> {
-    let cache_key = PermutationCacheKey::new(len, &set);
+pub fn create_permutations(set: &[Op], len: usize) -> HashSet<Vec<Op>> {
+    let cache_key = PermutationCacheKey::new(len, set.to_vec());
     if let Some(cached_value) = check_operator_set_cache(&cache_key) {
         return cached_value;
     }
     let mut permutations = HashSet::new();
-    create_permutations_recurse(&set, len, &mut permutations, vec![]);
+    create_permutations_recurse(set, len, &mut permutations, vec![]);
     store_operator_set_in_cache(cache_key, permutations.clone());
     permutations
 }