Solve Day 3 Part 1

data/examples/03.txt

@@ -0,0 +1 @@
+xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))

src/bin/03.rs

@@ -0,0 +1,38 @@
+advent_of_code::solution!(3);
+
+use regex::Regex;
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let re = Regex::new(r"mul\((\d+),(\d+)\)").unwrap();
+    let result = re
+        .captures_iter(input)
+        .filter_map(|x| {
+            let first = x[1].parse::<u32>().ok()?;
+            let second = x[2].parse::<u32>().ok()?;
+            Some(first * second)
+        })
+        .sum();
+
+    Some(result)
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    None
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(161));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, None);
+    }
+}