Add day3

day3/Cargo.lock

@@ -0,0 +1,61 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "aho-corasick"
+version = "1.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e60d3430d3a69478ad0993f19238d2df97c507009a52b3c10addcd7f6bcb916"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "day3"
+version = "0.1.0"
+dependencies = [
+ "once_cell",
+ "regex",
+]
+
+[[package]]
+name = "memchr"
+version = "2.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
+
+[[package]]
+name = "once_cell"
+version = "1.20.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1261fe7e33c73b354eab43b1273a57c8f967d0391e80353e51f764ac02cf6775"
+
+[[package]]
+name = "regex"
+version = "1.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b544ef1b4eac5dc2db33ea63606ae9ffcfac26c1416a2806ae0bf5f56b201191"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-automata",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-automata"
+version = "0.4.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "809e8dc61f6de73b46c85f4c96486310fe304c434cfa43669d7b40f711150908"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b15c43186be67a4fd63bee50d0303afffcef381492ebe2c5d87f324e1b8815c"

day3/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "day3"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+once_cell = "1.20.2"
+regex = "1.11.1"

day3/src/main.rs

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+use {once_cell::sync::Lazy, regex::Regex};
+
+fn part1(input: &str) -> u32 {
+    static RE: Lazy<Regex> = Lazy::new(|| Regex::new(r"mul\((\d{1,3}),(\d{1,3})\)").unwrap());
+    RE.captures_iter(input)
+        .map(|c| {
+            c.extract::<2>()
+                .1
+                .map(|d| d.parse::<u32>().unwrap())
+                .iter()
+                .product::<u32>()
+        })
+        .sum()
+}
+
+fn part2(input: &str) -> u32 {
+    input
+        .split(r"do()")
+        .map(|s| part1(s.split(r"don't()").next().unwrap()))
+        .sum()
+}
+
+fn main() {
+    let input = include_str!("../input.txt");
+    println!("{}", part1(input));
+    println!("{}", part2(input));
+}