feat: complete day 3 part 1

src/bin/03.rs

@@ -1,10 +1,28 @@
+use regex::Regex;
+
 advent_of_code::solution!(3);
 
 pub fn part_one(input: &str) -> Option<u32> {
-    None
+    // Define variables
+    let mut product: u32;
+    let mut result: u32 = 0;
+
+    // Extract each mul instruction using multiple regex capturing groups
+    let re = Regex::new(r"(mul\((\d{1,3}),(\d{1,3})\))").unwrap();
+
+    // Calculate the product of each mul instruction
+    for cap in re.captures_iter(input) {
+        let left_instruction: u32 = cap[2].parse::<u32>().unwrap();
+        let right_instruction: u32 = cap[3].parse::<u32>().unwrap();
+        product = left_instruction * right_instruction;
+        result += product;
+    }
+
+    // Return the total sum of products
+    Some(result)
 }
 
-pub fn part_two(input: &str) -> Option<u32> {
+pub fn part_two(_input: &str) -> Option<u32> {
     None
 }
 
@@ -21,6 +39,6 @@ mod tests {
     #[test]
     fn test_part_two() {
         let result = part_two(&advent_of_code::template::read_file("examples", DAY));
-        assert_eq!(result, None);
+        assert_eq!(result, Some(48));
     }
 }