Add day3

2024/day3/.gitignore

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+target
+input.txt

2024/day3/Cargo.lock

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+# 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 = [
+ "regex",
+]
+
+[[package]]
+name = "memchr"
+version = "2.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
+
+[[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"

2024/day3/Cargo.toml

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+[package]
+name = "day3"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+regex = "1.11.1"

2024/day3/src/main.rs

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+use std::fs;
+
+use regex::Regex;
+
+fn main() {
+    let file = fs::read_to_string("./input.txt").unwrap();
+    let lines = file.lines().collect::<Vec<&str>>();
+
+    println!("Solution 1: {}", puzzle1(&lines));
+    println!("Solution 2: {}", puzzle2(&lines));
+}
+
+fn puzzle1(lines: &[&str]) -> i32 {
+    let reg = Regex::new(r"mul\((\d{1,3}),(\d{1,3})\)").unwrap();
+
+    lines
+        .iter()
+        .map(|l| {
+            reg.captures_iter(l)
+                .map(|c| {
+                    let (_, [m1, m2]) = c.extract();
+                    m1.parse::<i32>().unwrap() * m2.parse::<i32>().unwrap()
+                })
+                .sum::<i32>()
+        })
+        .sum()
+}
+
+fn puzzle2(lines: &[&str]) -> i32 {
+    let reg = Regex::new(r"mul\((\d{1,3}),(\d{1,3})\)|do\(\)|don't\(\)").unwrap();
+
+    let mut enabled = true;
+    lines
+        .iter()
+        .map(|l| {
+            reg.captures_iter(l)
+                .map(|c| {
+                    let full = c.get(0).unwrap().as_str();
+                    if full.starts_with("don't") {
+                        enabled = false;
+                        return 0;
+                    } else if full.starts_with("do") {
+                        enabled = true;
+                        return 0;
+                    }
+                    let m1 = c.get(1).unwrap().as_str();
+                    let m2 = c.get(2).unwrap().as_str();
+                    if enabled {
+                        m1.parse::<i32>().unwrap() * m2.parse::<i32>().unwrap()
+                    } else {
+                        0
+                    }
+                })
+                .sum::<i32>()
+        })
+        .sum()
+}