Implemented day 3 part 2 solution

src/bin/day3.rs

@@ -1,6 +1,6 @@
 fn main() {
     let input = std::fs::read_to_string("input/3.txt").unwrap();
-    let (result1, result2) = (part1(&input), 0);
+    let (result1, result2) = (part1(&input), part2(&input));
     println!("Day 3");
     println!("Part 1: {}", result1);
     println!("Part 2: {}", result2);
@@ -59,3 +59,19 @@ fn part1(input: &str) -> u128 {
     result
 }
 
+fn part2(input: &str) -> u128 {
+    let lines: Vec<&str> = input.lines().collect();
+    let mut result = 0_u128;
+    for i in 1..lines.len() - 1 {
+        let line = lines[i];
+        for (j, c) in line.chars().enumerate() {
+            if c != '*' { continue; }
+            let numbers = adjacent_numbers(&lines, i, j);
+            if numbers.len() != 2 { continue; }
+            let prod: u128 = numbers.iter().product();
+            result += prod;
+        }
+    }
+    result
+}
+