From b428a21dca3d2421054f7c118c1b5b1d08ed8c47 Mon Sep 17 00:00:00 2001
From: mirsella <mirsella@protonmail.com>
Date: Tue, 3 Dec 2024 06:38:57 +0100
Subject: [PATCH] add day3

---
 2024/Cargo.toml       |  2 +-
 2024/day3/.gitignore  | 19 +++++++++++++++
 2024/day3/Cargo.toml  | 12 +++++++++
 2024/day3/build.rs    | 28 +++++++++++++++++++++
 2024/day3/src/main.rs | 57 +++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 117 insertions(+), 1 deletion(-)
 create mode 100644 2024/day3/.gitignore
 create mode 100644 2024/day3/Cargo.toml
 create mode 100644 2024/day3/build.rs
 create mode 100644 2024/day3/src/main.rs

diff --git a/2024/Cargo.toml b/2024/Cargo.toml
index 093b0cb..c562513 100644
--- a/2024/Cargo.toml
+++ b/2024/Cargo.toml
@@ -3,7 +3,7 @@ resolver = "2"
 members = [
   "day1",
   "day2",
-  # "day3",
+  "day3",
   # "day4",
   # "day5",
   # "day6",
diff --git a/2024/day3/.gitignore b/2024/day3/.gitignore
new file mode 100644
index 0000000..e983cca
--- /dev/null
+++ b/2024/day3/.gitignore
@@ -0,0 +1,19 @@
+input.txt
+flamegraph.svg
+perf.data*
+### Rust
+# Generated by Cargo
+# will have compiled files and executables
+debug/
+target/
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+
+# MSVC Windows builds of rustc generate these, which store debugging information
+*.pdb
+
diff --git a/2024/day3/Cargo.toml b/2024/day3/Cargo.toml
new file mode 100644
index 0000000..75e1a5a
--- /dev/null
+++ b/2024/day3/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "day3"
+authors = ["mirsella <mirsella@protonmail.com>"]
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+itertools = "0.13.0"
+regex = "1.11.1"
+
diff --git a/2024/day3/build.rs b/2024/day3/build.rs
new file mode 100644
index 0000000..b6a19a0
--- /dev/null
+++ b/2024/day3/build.rs
@@ -0,0 +1,28 @@
+use std::fs::File;
+use std::io::{self, Read};
+use std::path::PathBuf;
+use std::{env, fs};
+
+fn replace_in_file(file_path: &PathBuf, old: &str, new: &str) -> io::Result<()> {
+    let mut contents = String::new();
+    File::open(file_path)?.read_to_string(&mut contents)?;
+    let new_contents = contents.replace(old, new);
+    if contents != new_contents {
+        println!("Updating {}", file_path.display());
+        fs::write(file_path, new_contents)?;
+    }
+    Ok(())
+}
+
+fn main() -> io::Result<()> {
+    let pkg_name = env::var("CARGO_PKG_NAME").unwrap();
+    replace_in_file(
+        &"../Cargo.toml".into(),
+        &format!("# \"{pkg_name}\""),
+        &format!("\"{pkg_name}\""),
+    )?;
+
+    replace_in_file(&"./Cargo.toml".into(), "\n[workspace]", "")?;
+
+    Ok(())
+}
diff --git a/2024/day3/src/main.rs b/2024/day3/src/main.rs
new file mode 100644
index 0000000..0bd7a0d
--- /dev/null
+++ b/2024/day3/src/main.rs
@@ -0,0 +1,57 @@
+use itertools::Itertools;
+use regex::Regex;
+
+fn part1(input: &str) -> usize {
+    let regex = Regex::new(r"mul\((\d+),(\d+)\)").unwrap();
+    regex
+        .captures_iter(input)
+        .map(|c| {
+            c.extract::<2>()
+                .1
+                .into_iter()
+                .map(|s| s.parse::<usize>().unwrap())
+                .fold(0, |acc, v| if acc == 0 { v } else { acc * v })
+        })
+        .sum()
+}
+fn part2(input: &str) -> usize {
+    let regex = Regex::new(r"(mul\((\d+),(\d+)\)|don't\(\)|do\(\))").unwrap();
+    let mut acc = 0usize;
+    let mut enabled = true;
+    for capture in regex.captures_iter(input) {
+        let full = capture.get(0).unwrap().as_str();
+        if full == "don't()" {
+            enabled = false
+        } else if full == "do()" {
+            enabled = true
+        } else if full.starts_with("mul") {
+            if enabled {
+                acc += capture.get(2).unwrap().as_str().parse::<usize>().unwrap()
+                    * capture.get(3).unwrap().as_str().parse::<usize>().unwrap()
+            }
+        } else {
+            unreachable!();
+        }
+    }
+    acc
+}
+fn main() {
+    let input = include_str!("../input.txt");
+    println!("Part 1: {}", part1(input));
+    println!("Part 2: {}", part2(input));
+}
+
+#[cfg(test)]
+mod tests {
+    const INPUT: &str = "xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))";
+    #[test]
+    fn part1() {
+        assert_eq!(super::part1(INPUT), 161);
+    }
+    const INPUT2: &str =
+        "xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))";
+    #[test]
+    fn part2() {
+        assert_eq!(super::part2(INPUT2), 48);
+    }
+}