Solve day 3

Cargo.toml

@@ -32,6 +32,7 @@ either = "1.13.0"
 memchr = "2.7.4"
 pathsep = "0.1.1"
 regex = "1.11.1"
+void = "1.0.2"
 
 [target.'cfg(windows)'.dependencies]
 md-5 = "0.10.6"

src/2024/03.rs

@@ -0,0 +1,79 @@
+use eyre::Result;
+use regex::Regex;
+use void::Void;
+
+use crate::common::{TryFromStr, TryParse};
+use crate::meta::Problem;
+
+pub const MULL_IT_OVER: Problem = Problem::solved(
+    &|input| input.try_parse::<CorruptedMemory>()?.sum_of_products(),
+    &|input| {
+        input
+            .try_parse::<CorruptedMemory>()?
+            .conditional_sum_of_products()
+    },
+);
+
+struct CorruptedMemory<'i>(&'i str);
+
+impl<'i> TryFromStr<'i> for CorruptedMemory<'i> {
+    type Err = Void;
+
+    fn try_from_str(s: &'i str) -> Result<Self, Self::Err> {
+        Ok(Self(s))
+    }
+}
+
+thread_local! {
+    static MUL_RE: Regex = Regex::new(r"mul\((\d+),(\d+)\)").unwrap();
+}
+
+impl CorruptedMemory<'_> {
+    fn sum_of_products(&self) -> Result<usize> {
+        sum_products_in_str(self.0)
+    }
+
+    fn conditional_sum_of_products(&self) -> Result<usize> {
+        self.0
+            .split("do()")
+            .map(|chunk| {
+                chunk
+                    .split_once("don't()")
+                    .map_or(chunk, |(multiply_this, ..)| multiply_this)
+            })
+            .map(sum_products_in_str)
+            .try_fold(0, |a, res| res.map(|b| a + b))
+    }
+}
+
+fn sum_products_in_str(s: &str) -> Result<usize> {
+    MUL_RE.with(|re| {
+        re.captures_iter(s)
+            .map(|cap| -> Result<usize> {
+                let (_, [n_str, m_str]) = cap.extract();
+
+                let n = n_str.parse::<usize>()?;
+                let m = m_str.parse::<usize>()?;
+                Ok(n * m)
+            })
+            .try_fold(0usize, |a, res| res.map(|b| a + b))
+    })
+}
+
+#[test]
+fn part_1() {
+    static INPUT: &str =
+        r"xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))";
+
+    let memory: CorruptedMemory = INPUT.try_parse().unwrap();
+    assert_eq!(memory.sum_of_products().unwrap(), 161);
+}
+
+#[test]
+fn part_2() {
+    static INPUT: &str =
+        r"xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))";
+
+    let memory: CorruptedMemory = INPUT.try_parse().unwrap();
+    assert_eq!(memory.conditional_sum_of_products().unwrap(), 48);
+}

src/2024/mod.rs

@@ -2,5 +2,6 @@ use crate::meta::PROBLEMS;
 
 PROBLEMS! {
  01 => HISTORIAN_HYSTERIA,
- 02 => RED_NOSED_REPORTS
+ 02 => RED_NOSED_REPORTS,
+ 03 => MULL_IT_OVER
 }

tests/integration.rs

@@ -41,7 +41,8 @@ util::tests! {
 
     2024: {
         1: [2000468, 18567089],
-        2: [442]
+        2: [442],
+        3: [179834255, 80570939]
     }
 }