day-15 done and dusted

2023/day-15/src/part1.rs

@@ -0,0 +1,61 @@
+#![warn(clippy::all, clippy::pedantic)]
+
+/// day 15 part 1 of aoc 2023
+///
+/// # Arguments
+/// - input the input for today's puzzle
+///
+/// # Panics
+/// panics whne it cannot parse the input OR when ever the number of game numbers is greater than
+#[must_use]
+pub fn part1(input: &str) -> String {
+    input
+        .lines()
+        .map(|x| {
+            x.split(',')
+                .map(unhash)
+                .sum::<usize>()
+                .to_string()
+        })
+        .next()
+        .unwrap()
+}
+
+fn unhash(hash: &str) -> usize {
+    hash.chars()
+        .fold(0, |acc, x| (acc + (x as usize)) * 17 % 256)
+}
+
+#[cfg(test)]
+mod test {
+    use rstest::rstest;
+
+    use super::*;
+
+    #[rstest]
+    #[case("HASH", 52)]
+    #[case("rn=1", 30)]
+    #[case("cm-", 253)]
+    #[case("qp=3", 97)]
+    #[case("cm=2", 47)]
+    #[case("qp-", 14)]
+    #[case("pc=4", 180)]
+    #[case("ot=9", 9)]
+    #[case("ab=5", 197)]
+    #[case("pc-", 48)]
+    #[case("pc=6", 214)]
+    #[case("ot=7", 231)]
+    #[case("kqzb-\n", 127)]
+    #[case("dx-", 153)]
+    fn hash_test(#[case] input: &str, #[case] expected: usize) {
+        assert_eq!(unhash(input), expected);
+    }
+
+    const INPUT: &str = "rn=1,cm-,qp=3,cm=2,qp-,pc=4,ot=9,ab=5,pc-,pc=6,ot=7\n";
+
+    #[test]
+    fn part1_works() {
+        let result = part1(INPUT);
+        assert_eq!(result, "1320".to_string());
+    }
+}