Better permutation creation

day_07/src/equation/operator_set.rs

@@ -57,3 +57,27 @@ pub fn create_operator_set(num_of_operators: usize) -> HashSet<Vec<Op>> {
 
     operator_sets
 }
+
+fn create_permutations_recurse(
+    values: &HashSet<Op>,
+    len: usize,
+    permutations: &mut HashSet<Vec<Op>>,
+    curr_permutation: Vec<Op>,
+) {
+    if curr_permutation.len() == len {
+        permutations.insert(curr_permutation);
+        return;
+    }
+
+    for v in values {
+        let mut next_permutation = curr_permutation.clone();
+        next_permutation.push(*v);
+        create_permutations_recurse(values, len, permutations, next_permutation);
+    }
+}
+
+pub fn create_permutations(set: HashSet<Op>, len: usize) -> HashSet<Vec<Op>> {
+    let mut permutations = HashSet::new();
+    create_permutations_recurse(&set, len, &mut permutations, vec![]);
+    permutations
+}