day3 part2

src/day3.rs

@@ -18,10 +18,48 @@ fn get_joltage(line: &str) -> u32 {
     result
 }
 
+#[aoc(day3, part2)]
+pub fn part2(input: &str) -> u64 {
+    input
+        .split("\n")
+        .map(|line| get_joltage_rec(line, 12, 0))
+        .sum()
+}
+
+fn get_joltage_rec(line: &str, num: usize, acc: u64) -> u64 {
+    if num < 1 {
+        return acc;
+    }
+    let len = line.len();
+    let (revpos, val) = line[..(len - num + 1)]
+        .chars()
+        .rev()
+        .enumerate()
+        .max_by(|x, y| x.1.cmp(&y.1))
+        .unwrap();
+    let pos = len - num - revpos;
+    get_joltage_rec(
+        &line[(pos + 1)..],
+        num - 1,
+        acc * 10 + val.to_digit(10).unwrap() as u64,
+    )
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
 
+    #[test]
+    fn test_part2_1() {
+        let input = String::from(
+            "987654321111111
+811111111111119
+234234234234278
+818181911112111",
+        );
+        assert_eq!(part2(&input), 3121910778619)
+    }
+
     #[test]
     fn test_part1_1() {
         let input = String::from(
@@ -32,6 +70,7 @@ mod tests {
         );
         assert_eq!(part1(&input), 357)
     }
+
     #[test]
     fn test_part1_2() {
         let input = String::from(