Solve day 10

src/2015/10.rs

@@ -0,0 +1,37 @@
+use eyre::Result;
+use itertools::Itertools;
+
+use crate::types::{problem, Problem};
+
+pub const ELVES_LOOK_ELVES_SAY: Problem = problem!(part1, part2);
+
+fn part1(input: &str) -> Result<usize> {
+    let mut n = input.to_string();
+    dbg!(&n);
+    for _ in 0..40 {
+        n = look_and_say(&n);
+        dbg!(&n);
+    }
+
+    Ok(n.len())
+}
+
+fn part2(input: &str) -> Result<usize> {
+    let mut n = input.to_string();
+    for _ in 0..50 {
+        n = look_and_say(&n);
+    }
+
+    Ok(n.len())
+}
+
+fn look_and_say(n: &str) -> String {
+    let mut out = String::new();
+    for (digit, group) in &n.to_string().chars().chunk_by(|ch| *ch) {
+        let num_repetitions = group.count().to_string();
+        out.push_str(&num_repetitions);
+        out.push(digit);
+    }
+
+    out
+}

src/2015/mod.rs

@@ -3,7 +3,7 @@ use phf::phf_map;
 use crate::types::ProblemSet;
 use crate::util::mod_days;
 
-mod_days!(1, 2, 3, 4, 5, 6, 7, 8, 9);
+mod_days!(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
 
 pub const PROBLEMS: ProblemSet = ProblemSet(phf_map! {
     1u8 => NOT_QUITE_LISP,
@@ -14,5 +14,6 @@ pub const PROBLEMS: ProblemSet = ProblemSet(phf_map! {
     6u8 => PROBABLY_A_FIRE_HAZARD,
     7u8 => SOME_ASSEMBLY_REQUIRED,
     8u8 => MATCHSTICKS,
-    9u8 => ALL_IN_A_SINGLE_NIGHT
+    9u8 => ALL_IN_A_SINGLE_NIGHT,
+    10u8 => ELVES_LOOK_ELVES_SAY
 });

tests/2015.rs

@@ -107,3 +107,15 @@ mod day9 {
         crate::util::aoc!(2015/9-2: 898);
     }
 }
+
+mod day10 {
+    #[test]
+    fn part1() {
+        crate::util::aoc!(2015/10-1: 360154);
+    }
+
+    #[test]
+    fn part2() {
+        crate::util::aoc!(2015/10-2: 5103798);
+    }
+}