day_3: part 2 done

src/advent_of_code/mod.rs

@@ -27,4 +27,10 @@ pub fn historian_hysteria() {
         "The result of the sum of multiplications is {}",
         multiplication_added_result
     );
+    let conditional_multiplication_added_result =
+        tue_03::mull_it_over_conditional("./assets/day_3_instruction_input");
+    println!(
+        "The result of the conditional sum of multiplications is {}",
+        conditional_multiplication_added_result
+    );
 }

src/advent_of_code/tue_03.rs

@@ -18,6 +18,57 @@ pub fn mull_it_over(input: &str) -> MulNumber {
     sum_result
 }
 
+pub fn mull_it_over_conditional(input: &str) -> MulNumber {
+    let instruction_input = read_instruction_input(input);
+
+    let find_condition_and_multiply_regex =
+        Regex::new(r"(do\(\)|don't\(\).*?mul\([0-9]+,[0-9]+\)|.*?mul\([0-9]+,[0-9]+\))").unwrap();
+    let separate_condition_and_multiply_regex =
+        Regex::new(r"(do\(\)|don't\(\)).*?(mul\([0-9]+,[0-9]+\))").unwrap();
+    let mul_regex = Regex::new(r"(mul\([0-9]+,[0-9]+\))").unwrap();
+    let conditional_regex = Regex::new(r"(do\(\)|don't\(\))").unwrap();
+
+    let mut sum_result: MulNumber = 0;
+    let mut current_do_condition: bool = true;
+
+    for conditional_mul in find_condition_and_multiply_regex.captures_iter(&instruction_input) {
+        if let Some(operation_pair) =
+            separate_condition_and_multiply_regex.captures(&conditional_mul[1])
+        {
+            // conditional AND mul present
+            let next_conditional = conditional_regex.captures(&operation_pair[1]);
+            if let Some(c) = next_conditional {
+                if &c[1] == "do()" {
+                    current_do_condition = true;
+                } else {
+                    current_do_condition = false;
+                }
+            }
+            if let Some(o) = mul_regex.captures(&operation_pair[2]) {
+                if current_do_condition {
+                    let multiplication_result = process_mul_operation(&o[1]);
+                    sum_result += multiplication_result;
+                }
+            }
+        } else if let Some(c) = conditional_regex.captures(&conditional_mul[1]) {
+            // only conditional present
+            if &c[1] == "do()" {
+                current_do_condition = true;
+            } else {
+                current_do_condition = false;
+            }
+        } else if let Some(o) = mul_regex.captures(&conditional_mul[1]) {
+            // only mul present
+            if current_do_condition {
+                let multiplication_result = process_mul_operation(&o[1]);
+                sum_result += multiplication_result;
+            }
+        }
+    }
+
+    sum_result
+}
+
 fn process_mul_operation(operation: &str) -> MulNumber {
     let mul_regex = Regex::new(r"mul\(([0-9]+),([0-9]+)\)").unwrap();