diff --git a/aoc-py/solutions/day20.py b/aoc-py/solutions/day20.py
index fb0cabd..4a6d4bd 100644
--- a/aoc-py/solutions/day20.py
+++ b/aoc-py/solutions/day20.py
@@ -103,10 +103,10 @@ def _parse_input(self, inp: str) -> tuple[dict[str, Module], list[str]]:
                     # defaulting to false to begin
                     module.memory[name] = False
         return modules, broadcast_targets
-    
+
     def _run_modules(self, destinations: list[Destination], module: Module, source: str, pulse: bool) -> None:
         """Runs a single iteration of all the modules' pulse sending process"""
-        
+
         if isinstance(module, Flipper) and not pulse:
             module.status = not module.status
             pulse_to_send = module.status
@@ -176,8 +176,8 @@ def part_two(self, inp: str) -> int:
                         seen[name := source.name] = True
 
                         if name not in press_amounts:
-                            press_amounts[name] = n_presses 
-                        
+                            press_amounts[name] = n_presses
+
                         if all(seen.values()):
                             # we have checked all the modules that feed into the module
                             # we can then return the result
diff --git a/src/bin/day19.rs b/src/bin/day19.rs
index 1da23e5..160a6fe 100644
--- a/src/bin/day19.rs
+++ b/src/bin/day19.rs
@@ -8,15 +8,13 @@ use std::{
 };
 use aoc_2023::Solution;
 
-pub struct Day19;
-
 #[derive(Debug, Clone)]
 struct Rule<'a> {
-    pub key: &'a str,
-    pub target: &'a str,
-    pub rhs: usize,
-    pub is_gt: bool,
-    pub condition: fn(&usize, &usize) -> bool,
+    key: &'a str,
+    target: &'a str,
+    rhs: usize,
+    is_gt: bool,
+    condition: fn(&usize, &usize) -> bool,
 }
 
 impl<'a> Rule<'a> {
@@ -29,8 +27,8 @@ impl<'a> Rule<'a> {
 
 #[derive(Debug, Clone)]
 struct Workflow<'a> {
-    pub default: &'a str,
-    pub rules: Vec<Rule<'a>>,
+    default: &'a str,
+    rules: Vec<Rule<'a>>,
 }
 
 impl<'a> Workflow<'a> {
@@ -54,7 +52,7 @@ impl<'a> Workflow<'a> {
                 if is_gt { '>' } else { '<' }
             )
                 .unwrap();
-            
+
             self.rules.push(Rule {
                 key, target, is_gt,
                 rhs: rhs.parse::<usize>()
@@ -66,6 +64,8 @@ impl<'a> Workflow<'a> {
     }
 }
 
+pub struct Day19;
+
 impl Day19 {
     fn parse_workflows<T>(raw: &T) -> HashMap<String, Workflow<'_>>
     where
@@ -200,7 +200,7 @@ impl Day19 {
     }
 
     /// # Panics
-    /// 
+    ///
     /// If failed to parse input (malformed)
     pub fn part_one<T: Display>(&self, inp: T) -> usize {
         let inp = inp
@@ -219,9 +219,9 @@ impl Day19 {
             )
             .sum()
     }
-    
+
     /// # Panics
-    /// 
+    ///
     /// If failed to parse input (malformed)
     pub fn part_two<T: Display>(&self, inp: T) -> usize {
         let inp = inp
diff --git a/src/bin/day20.rs b/src/bin/day20.rs
new file mode 100644
index 0000000..57756cb
--- /dev/null
+++ b/src/bin/day20.rs
@@ -0,0 +1,147 @@
+//! Day 20: Pulse Propagation
+//!
+//! <https://adventofcode.com/2023/day/20>
+use std::{
+    collections::{VecDeque, HashMap},
+    fmt::Display, os::windows::io::BorrowedHandle,
+};
+use aoc_2023::Solution;
+
+#[derive(Debug, Clone)]
+struct Destination {
+    name: String,
+    target: String,
+    pulse: bool,
+}
+
+#[derive(Debug, Clone)]
+enum Module<'a> {
+    Flipper {
+        name: &'a str,
+        outputs: Vec<String>,
+        status: bool,
+    },
+    Conjunction {
+        name: &'a str,
+        outputs: Vec<String>,
+        memory: HashMap<String, bool>,
+    }
+}
+
+impl<'a> Module<'a> {
+    fn new(raw: &'a str, outputs: Vec<String>) -> Self {
+        match raw
+            .split_at(1)
+        {
+            ("%", name) => Self::Flipper {
+                name, outputs,
+                status: false,
+            },
+            ("&", name) => Self::Conjunction {
+                name, outputs,
+                memory: HashMap::new(),
+            },
+            _ => panic!("Invalid module prefix"),
+        }
+    }
+
+    fn name(&self) -> &'a str {
+        match self {
+            Self::Flipper { name, .. } => name,
+            Self::Conjunction { name, .. } => name,
+        }
+    }
+
+    fn outputs(&self) -> &Vec<String> {
+        match self {
+            Self::Flipper { outputs, .. } => outputs,
+            Self::Conjunction { outputs, .. } => outputs,
+        }
+    }
+}
+
+pub struct Day20;
+
+impl Day20 {
+    fn parse_input<T>(inp: &T) -> (HashMap<String, Module<'_>>, Vec<String>)
+    where
+        T: AsRef<str>,
+    {
+        let mut modules = HashMap::new();
+        let mut broadcast_targets = Vec::new();
+
+        for line in inp
+            .as_ref()
+            .lines()
+        {
+            let (name, targets) = line
+                .split_once("->")
+                .unwrap();
+            let targets = targets
+                .split(',')
+                .map(|s| s.trim().to_string())
+                .collect::<Vec<String>>();
+            match name.trim() {
+                "broadcaster" => broadcast_targets = targets,
+                name => {
+                    modules.insert(
+                        name.to_string(),
+                        Module::new(name, targets),
+                    );
+                }
+            }
+        }
+
+        for (name, module) in &modules {
+            for output in module
+                .outputs()
+                .iter()
+                .filter_map(|output| modules
+                    .get_mut(output)
+                )
+            {
+                if let Module::Conjunction { memory, .. } = output {
+                    memory.insert(
+                        name.clone(),
+                        false
+                    );
+                }
+            }
+        }
+        (modules, broadcast_targets)
+    }
+    pub fn part_one<T: Display>(&self, inp: T) -> usize {
+        todo!()
+    }
+
+    pub fn part_two<T: Display>(&self, inp: T) -> usize {
+        todo!()
+    }
+}
+
+impl Solution for Day20 {
+    const NAME: &'static str = "Pulse Propagation";
+
+    fn run(&self, inp: String) {
+        let p1 = self.part_one(&inp);
+        let p2 = self.part_two(&inp);
+
+        println!("Part 1: {p1}");
+        println!("Part 2: {p2}");
+
+        assert_eq!(p1, 680_278_040);
+        assert_eq!(p2, 243_548_140_870_057);
+    }
+}
+
+fn main() {
+    aoc_2023::run_day(20, &Day20);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() { main(); }
+}
\ No newline at end of file