diff --git a/Cargo.lock b/Cargo.lock
index d90c668..230dadf 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -17,6 +17,15 @@ version = "2.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "512761e0bb2578dd7380c6baaa0f4ce03e84f95e960231d1dec8bf4d7d6e2627"
 
+[[package]]
+name = "aho-corasick"
+version = "1.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e60d3430d3a69478ad0993f19238d2df97c507009a52b3c10addcd7f6bcb916"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "ansi_term"
 version = "0.12.1"
@@ -43,6 +52,7 @@ dependencies = [
  "colored",
  "lazy_static",
  "mut_static",
+ "regex",
  "reqwest",
 ]
 
@@ -837,6 +847,35 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[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"
+
 [[package]]
 name = "reqwest"
 version = "0.11.27"
diff --git a/Cargo.toml b/Cargo.toml
index 3609d01..4e2fb1a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,6 +12,7 @@ aoc-macro = {path="aoc-macro"}
 reqwest = { version = "0.11", features=["cookies", "blocking"] }
 mut_static="5.0"
 lazy_static="1.4"
+regex = "1.11"
 
 [profile.release]
 opt-level = 3
diff --git a/README.md b/README.md
index 6d57704..5b0b40b 100644
--- a/README.md
+++ b/README.md
@@ -3,8 +3,8 @@
 [![About](https://img.shields.io/badge/Advent%20of%20Code-2024-brightgreen?style=flat-square)](https://adventofcode.com/2024/about)
 [![Language: Rust](https://img.shields.io/badge/Language-Rust-orange.svg?style=flat-square)](https://en.wikipedia.org/wiki/Rust_(programming_language))
 [![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg?style=flat-square)](https://mit-license.org/)
-![Days completed](https://img.shields.io/badge/Days%20completed-1-red?style=flat-square)
-![Stars](https://img.shields.io/badge/Stars-3-yellow?style=flat-square)
+![Days completed](https://img.shields.io/badge/Days%20completed-2.5-red?style=flat-square)
+![Stars](https://img.shields.io/badge/Stars-5-yellow?style=flat-square)
 
 > ⚠️ This README is copied from my previous years solution. It is not fully adopted to 2024 yet.
 
diff --git a/src/days/d03.rs b/src/days/d03.rs
index 59c0ad7..3a06482 100644
--- a/src/days/d03.rs
+++ b/src/days/d03.rs
@@ -1,32 +1,88 @@
 use super::{Answer, Day, DayImpl};
+use regex::Regex;
 
 const CURRENT_DAY: u8 = 3;
 
-type Data = Vec<u64>;
+#[derive(Clone, Debug)]
+pub struct Command {
+    command: String,
+    parameters: Vec<u64>,
+}
+
+impl Command {
+    pub fn run(&self) -> u64 {
+        if !self.command.ends_with("mul") || self.parameters.len() < 2 {
+            return 0;
+        }
+        self.parameters[0] * self.parameters[1]
+    }
+}
+
+#[derive(Clone, Debug)]
+pub struct Program(Vec<Command>);
+
+impl Program {
+    pub fn do_all_multiplications(&self) -> u64 {
+        self.0.iter().map(|v| v.run()).sum()
+    }
+
+    pub fn run(&self) -> u64 {
+        let mut enabled = true;
+
+        self.0
+            .iter()
+            .map(|v| {
+                if v.command.ends_with("don't") {
+                    enabled = false;
+                } else if v.command.ends_with("do") {
+                    enabled = true;
+                } else if enabled {
+                    return v.run();
+                }
+                0
+            })
+            .sum()
+    }
+}
+
+impl From<&str> for Program {
+    fn from(value: &str) -> Self {
+        let pattern: Regex = Regex::new(r"([a-z_']+)\(((?:\d+,?)*)\)").unwrap();
+
+        let mut commands = vec![];
+        for (_, [command, parameters]) in pattern.captures_iter(value).map(|c| c.extract()) {
+            commands.push(Command {
+                command: command.to_string(),
+                parameters: parameters
+                    .split(",")
+                    .map(|v| v.parse().unwrap_or(0))
+                    .collect(),
+            });
+        }
+
+        Self(commands)
+    }
+}
+
+type Data = Program;
 impl DayImpl<Data> for Day<CURRENT_DAY> {
     fn init_test() -> (Self, Data) {
         Self::init(include_str!("test_inputs/test03.txt"))
     }
 
     fn expected_results() -> (Answer, Answer) {
-        (Answer::Number(0), Answer::Number(0))
+        (Answer::Number(161), Answer::Number(0))
     }
 
     fn init(input: &str) -> (Self, Data) {
-        (
-            Self {},
-            input
-                .lines()
-                .map(|v| v.parse::<u64>().expect("error while parsing input."))
-                .collect(),
-        )
+        (Self {}, input.into())
     }
 
     fn one(&self, data: &mut Data) -> Answer {
-        Answer::Number(data.len() as u64)
+        Answer::Number(data.do_all_multiplications())
     }
 
     fn two(&self, data: &mut Data) -> Answer {
-        Answer::Number(data.len() as u64)
+        Answer::Number(data.run())
     }
 }
diff --git a/src/days/test_inputs/test03.txt b/src/days/test_inputs/test03.txt
index e69de29..b774ec9 100644
--- a/src/days/test_inputs/test03.txt
+++ b/src/days/test_inputs/test03.txt
@@ -0,0 +1 @@
+xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))
\ No newline at end of file