Use Arc to not clone cached permutations

day_07/src/equation.rs

@@ -1,6 +1,8 @@
 mod operator_set;
 
-use operator_set::{Op, create_operator_set};
+use std::ops::Deref;
+
+use operator_set::{Op, create_permutations};
 
 #[derive(Debug)]
 pub struct Equation {
@@ -46,10 +48,6 @@ impl Equation {
         self.answer
     }
 
-    pub fn components(&self) -> &Vec<i64> {
-        &self.components
-    }
-
     fn compute_answer(&self, operators: &[Op]) -> i64 {
         let mut accumulator = self.components[0];
 
@@ -57,17 +55,39 @@ impl Equation {
             match op {
                 Op::Multiply => accumulator *= self.components[i + 1],
                 Op::Add => accumulator += self.components[i + 1],
+                Op::Concat => {
+                    let accumulator_string = format!("{}", accumulator);
+                    let component_string = format!("{}", self.components[i + 1]);
+                    accumulator = (accumulator_string + &component_string).parse().unwrap();
+                }
             }
         }
 
         accumulator
     }
 
-    pub fn solvable(&self) -> bool {
-        let op_combinations = create_operator_set(self.components.len() - 1);
+    const MULTIPLY_ADD_SET: [Op; 2] = [Op::Add, Op::Multiply];
+    pub fn solvable_multiply_add(&self) -> bool {
+        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) {
+        for combination in op_combinations.deref() {
+            if self.answer == self.compute_answer(combination) {
+                return true;
+            }
+        }
+        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(
+            &Equation::MULTIPLY_ADD_CONCAT_SET,
+            self.components.len() - 1,
+        );
+
+        for combination in op_combinations.deref() {
+            if self.answer == self.compute_answer(combination) {
                 return true;
             }
         }

day_07/src/equation/operator_set.rs

@@ -1,59 +1,79 @@
 use std::collections::HashMap;
 use std::collections::HashSet;
-use std::sync::{LazyLock, Mutex};
+use std::sync::{Arc, LazyLock, Mutex};
 
 #[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
 pub enum Op {
     Multiply,
     Add,
+    Concat,
 }
 
-type OperatorCache = HashMap<usize, HashSet<Vec<Op>>>;
+#[derive(Debug, Clone, Hash, PartialEq, Eq)]
+struct PermutationCacheKey {
+    size: usize,
+    set: Vec<Op>,
+}
+
+impl PermutationCacheKey {
+    fn new(size: usize, set: Vec<Op>) -> PermutationCacheKey {
+        PermutationCacheKey { size, set }
+    }
+}
+
+type Permutation = Vec<Op>;
+type OperatorCache = HashMap<PermutationCacheKey, Arc<HashSet<Permutation>>>;
 
 static OPERATOR_SET_CACHE: LazyLock<Mutex<OperatorCache>> =
     LazyLock::new(|| Mutex::new(HashMap::new()));
 
-fn check_operator_set_cache(cache_key: usize) -> Option<HashSet<Vec<Op>>> {
-    OPERATOR_SET_CACHE.lock().unwrap().get(&cache_key).cloned()
+fn check_operator_set_cache(cache_key: &PermutationCacheKey) -> Option<Arc<HashSet<Permutation>>> {
+    let lock = OPERATOR_SET_CACHE.lock().unwrap();
+    let cache_value = lock.get(cache_key);
+    cache_value.cloned()
 }
 
-fn store_operator_set_in_cache(cache_key: usize, cache_value: HashSet<Vec<Op>>) {
+fn store_operator_set_in_cache(
+    cache_key: PermutationCacheKey,
+    cache_value: Arc<HashSet<Permutation>>,
+) {
     OPERATOR_SET_CACHE
         .lock()
         .unwrap()
         .insert(cache_key, cache_value);
 }
 
-fn create_operator_set_recurse(
-    operators_permutation_set: &mut HashSet<Vec<Op>>,
-    operators: Vec<Op>,
+fn create_permutations_recurse(
+    values: &[Op],
+    len: usize,
+    permutations: &mut HashSet<Permutation>,
+    curr_permutation: Permutation,
 ) {
-    operators_permutation_set.insert(operators.clone());
-    if !operators.contains(&Op::Add) {
+    if curr_permutation.len() == len {
+        permutations.insert(curr_permutation);
         return;
     }
 
-    for i in 0..operators.len() {
-        if operators[i] == Op::Multiply {
-            break;
-        }
-        let mut new_operators = operators.clone();
-        new_operators[i] = Op::Multiply;
-        create_operator_set_recurse(operators_permutation_set, new_operators);
+    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_operator_set(num_of_operators: usize) -> HashSet<Vec<Op>> {
+pub fn create_permutations(set: &[Op], len: usize) -> Arc<HashSet<Permutation>> {
     // Check cache
-    if let Some(cached_value) = check_operator_set_cache(num_of_operators) {
-        return cached_value.clone();
+    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 operator_sets: HashSet<Vec<Op>> = HashSet::new();
-    create_operator_set_recurse(&mut operator_sets, vec![Op::Add; num_of_operators]);
+    // Create permutations
+    let mut permutations = HashSet::new();
+    create_permutations_recurse(set, len, &mut permutations, vec![]);
 
-    // Store value in cache
-    store_operator_set_in_cache(num_of_operators, operator_sets.clone());
-
-    operator_sets
+    // Cache and return
+    let permutations = Arc::new(permutations);
+    store_operator_set_in_cache(cache_key, permutations.clone());
+    permutations
 }

day_07/src/main.rs

@@ -33,19 +33,34 @@ fn main() -> Result<(), Box<dyn Error>> {
         equations.push(Equation::new(&line)?)
     }
 
-    let mut value_sum = 0;
+    let mut result_add_multiply = 0;
+    let mut result_add_multiply_concat = 0;
 
     println!("Is solvable?");
     println!("------------");
     for equation in equations {
-        let solvable = equation.solvable();
-        println!("{:?} => {}", equation, solvable);
-        if solvable {
-            value_sum += equation.answer();
+        let solvable_add_multiply = equation.solvable_multiply_add();
+        let solvable_add_multiply_concat = equation.solvable_multiply_add_concat();
+        println!(
+            "{:?} => {} | {}",
+            equation, solvable_add_multiply, solvable_add_multiply_concat
+        );
+        if solvable_add_multiply {
+            result_add_multiply += equation.answer();
+        }
+        if solvable_add_multiply_concat {
+            result_add_multiply_concat += equation.answer();
         }
     }
 
-    println!("\n Total Calibration Result: {}", value_sum);
+    println!(
+        "\n Total Calibration Result (ADD|MULTIPLY): {}",
+        result_add_multiply
+    );
+    println!(
+        "\n Total Calibration Result (ADD|MULTIPLY|CONCAT): {}",
+        result_add_multiply_concat
+    );
 
     Ok(())
 }