wip: cloned graph

data/examples/20.txt

@@ -0,0 +1,5 @@
+broadcaster -> a, b, c
+%a -> b
+%b -> c
+%c -> inv
+&inv -> a

src/bin/20.rs

@@ -0,0 +1,187 @@
+use std::{
+    collections::{HashMap, VecDeque},
+    mem::swap,
+    str::FromStr,
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+enum Module {
+    Broadcaster,
+    FlipFlop(bool),
+    Conjuction,
+}
+
+#[derive(Debug)]
+struct ParseModuleError;
+
+impl FromStr for Module {
+    type Err = ParseModuleError;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Ok(match s {
+            "%" => Module::FlipFlop(false),
+            "&" => Module::Conjuction,
+            _ => Module::Broadcaster,
+        })
+    }
+}
+
+#[derive(Debug)]
+struct Node {
+    index: usize,
+    module: Module,
+    inputs: Vec<usize>,
+    outputs: Vec<usize>,
+}
+
+fn parse_input(input: &str) -> Vec<Node> {
+    let mut nodes = Vec::new();
+    let mut mapper: HashMap<String, usize> = HashMap::new();
+
+    for line in input.lines() {
+        let (from, _) = line.split_once(" -> ").unwrap();
+        let (module, mut name) = from.split_at(1);
+        let module: Module = module.parse().unwrap();
+        if module == Module::Broadcaster {
+            name = from;
+        }
+
+        *mapper.entry(name.to_string()).or_default() = nodes.len();
+
+        let l = Node {
+            module,
+            index: nodes.len(),
+            inputs: Vec::new(),
+            outputs: Vec::new(),
+        };
+
+        nodes.push(l);
+    }
+
+    for line in input.lines() {
+        let (from, to) = line.split_once(" -> ").unwrap();
+        let (module, mut name) = from.split_at(1);
+        let module: Module = module.parse().unwrap();
+        if module == Module::Broadcaster {
+            name = from;
+        }
+
+        let index = mapper[name];
+        for destination in to.split(", ") {
+            let to_index = mapper[destination];
+            nodes[index].outputs.push(to_index);
+            nodes[to_index].inputs.push(index);
+        }
+    }
+
+    nodes
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    let mut nodes = parse_input(input);
+
+    let mut graph = vec![vec![None; nodes.len()]; nodes.len()];
+
+    let mut highs = 0;
+    let mut lows = 0;
+
+    let broadcaster = nodes
+        .iter()
+        .find(|x| x.module == Module::Broadcaster)?
+        .index;
+
+    for _ in 0..1000 {
+        let mut stack = VecDeque::from([broadcaster]);
+        while !stack.is_empty() {
+            let mut new_stack = VecDeque::new();
+            let mut new_graph = graph.clone();
+
+            while let Some(index) = stack.pop_front() {
+                let node = &nodes[index];
+                let mut new_module = None;
+
+                match node.module {
+                    Module::Broadcaster => {
+                        for dest_index in node.outputs.iter() {
+                            new_graph[index][*dest_index] = Some(false);
+                            new_stack.push_back(*dest_index);
+                            lows += 1;
+                        }
+                    }
+                    Module::FlipFlop(high) => {
+                        let mut swapper = None;
+                        for in_index in nodes[index].inputs.iter() {
+                            let value = &mut graph[*in_index][index];
+                            if value.is_some() {
+                                debug_assert!(swapper.is_none());
+                                swap(&mut swapper, value);
+                            }
+                        }
+
+                        if !swapper.unwrap() {
+                            let signal = !high;
+
+                            for dest_index in nodes[index].outputs.iter() {
+                                new_graph[index][*dest_index] = Some(signal);
+                                new_stack.push_back(*dest_index);
+                                if signal {
+                                    highs += 1;
+                                } else {
+                                    lows += 1;
+                                }
+                            }
+
+                            new_module = Some(Module::FlipFlop(signal));
+                        }
+                    }
+                    Module::Conjuction => {
+                        let mut all = true;
+
+                        for in_index in nodes[index].inputs.iter() {
+                            let value = graph[*in_index][index];
+                            all &= value.unwrap_or(false);
+                        }
+
+                        for dest_index in nodes[index].outputs.iter() {
+                            new_graph[index][*dest_index] = Some(!all);
+                            new_stack.push_back(*dest_index);
+                            if !all {
+                                highs += 1;
+                            } else {
+                                lows += 1;
+                            }
+                        }
+                    }
+                }
+
+                let node = &mut nodes[index];
+                if let Some(module) = new_module {
+                    node.module = module;
+                }
+            }
+
+            stack = new_stack;
+            graph = new_graph;
+        }
+    }
+
+    Some(highs * lows)
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    None
+}
+
+aoc::solution!(20);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        assert_eq!(part_one(&aoc::template::read_file("examples", 20)), None);
+    }
+    #[test]
+    fn test_part_two() {
+        assert_eq!(part_two(&aoc::template::read_file("examples", 20)), None);
+    }
+}