day 1 part 2

day1/src/main.rs

@@ -6,28 +6,49 @@ fn main() {
     println!("Result: {}", result);
 }
 
-fn calibration_value(input: &str) -> u32 {
-    input.lines()
-        .map(|line| {
-            let digits: Vec<char> = line.chars().filter(|c| c.is_numeric()).collect();
+const VALUES: [&str; 18] = [
+    "1", "2", "3", "4", "5", "6", "7", "8", "9", "one", "two", "three", "four", "five", "six",
+    "seven", "eight", "nine",
+];
+
+fn calibration_value(input: &str) -> u32 {
+    input
+        .lines()
+        .map(|line| {
+            let (_, first) = VALUES
+                .iter()
+                .enumerate()
+                .filter_map(|(vi, s)| line.find(s).map(|ri| (ri, (vi % 9) as u32 + 1)))
+                .min_by_key(|(i, _v)| *i)
+                .unwrap();
+            let (_, last) = VALUES
+                .iter()
+                .enumerate()
+                .filter_map(|(vi, s)| line.rfind(s).map(|ri| (ri, (vi % 9) as u32 + 1)))
+                .max_by_key(|(i, _v)| *i)
+                .unwrap();
 
-            let first = digits.first().unwrap().to_digit(10).unwrap();
-            let last = digits.last().unwrap().to_digit(10).unwrap();
             dbg!(first * 10 + last)
         })
         .sum()
 }
 
-
 #[cfg(test)]
 mod tests {
     use crate::calibration_value;
 
-    const EXAMPLE: &str = "1abc2\npqr3stu8vwx\na1b2c3d4e5f\ntreb7uchet";
+    const EXAMPLE_PART_1: &str = "1abc2\npqr3stu8vwx\na1b2c3d4e5f\ntreb7uchet";
+    const EXAMPLE_PART_2: &str = "two1nine\neightwothree\nabcone2threexyz\nxtwone3four\n4nineeightseven2\nzoneight234\n7pqrstsixteen";
 
     #[test]
-    fn example() {
-        let result = calibration_value(EXAMPLE);
+    fn example_part_1() {
+        let result = calibration_value(EXAMPLE_PART_1);
         assert_eq!(142, result);
     }
-}
+
+    #[test]
+    fn example_part_2() {
+        let result = calibration_value(EXAMPLE_PART_2);
+        assert_eq!(281, result);
+    }
+}