day20

src/day20.rs

@@ -0,0 +1,220 @@
+use std::collections::{HashMap, VecDeque};
+
+use aoc_runner_derive::{aoc, aoc_generator};
+use num::Integer;
+
+#[derive(Debug, Clone)]
+enum Module {
+    FlipFlop { state: bool, dests: Vec<String> },
+    Conjunction { state: HashMap<String, bool>, dests: Vec<String> },
+    Broadcast { dests: Vec<String> },
+}
+
+#[aoc_generator(day20)]
+fn parse(input: &str) -> HashMap<String, Module> {
+    let mut input: HashMap<_, _> = input.lines().map(|line| {
+        let (name, dests) = line.split_once("->").unwrap();
+        let dests = parse_destinations(dests);
+        let module = parse_module(name.trim(), dests);
+        (name.trim_matches(['&', '%', ' '].as_slice()).to_string(), module)
+    }).collect();
+    collect_inputs(&mut input);
+    input
+}
+
+fn parse_module(name: &str, dests: Vec<String>) -> Module {
+    match name {
+        "broadcaster" => Module::Broadcast { dests },
+        name if name.starts_with('%') => Module::FlipFlop { state: false, dests },
+        name if name.starts_with('&') => Module::Conjunction { state: HashMap::new(), dests },
+        _ => panic!("Invalid Module {}", name)
+    }
+
+}
+
+fn collect_inputs(modules: &mut HashMap<String, Module>) {
+    for (name, module) in modules.clone() {
+        let dests = match module {
+            Module::FlipFlop { state: _, dests: dest } => dest,
+            Module::Conjunction { state: _, dests: dest } => dest,
+            Module::Broadcast { dests: dest } => dest,
+        };
+
+        for dest_name in dests {
+            if let Some(dest_mod) = modules.get_mut(&dest_name) {
+                match dest_mod {
+                    Module::Conjunction { state, dests: _ } => state.insert(name.to_string(), false),
+                    _ => continue
+                };
+            }
+        }
+    }
+}
+
+fn parse_destinations(dests: &str) -> Vec<String> {
+    dests.split(',')
+        .map(|x| x.trim().to_string())
+        .collect::<Vec<String>>()
+}
+
+#[aoc(day20, part1)]
+fn part1(modules: &HashMap<String, Module>) -> usize {
+    let mut modules = modules.clone();
+    let mut high: usize = 0;
+    let mut low: usize = 0;
+    for _ in 0..1000 {
+        let (high_pulses, low_pulses) = push_the_button(&mut modules);
+        high += high_pulses;
+        low += low_pulses;
+    }
+
+    high * low
+}
+
+fn push_the_button(modules: &mut HashMap<String, Module>) -> (usize, usize) {
+    let mut process_queue: VecDeque<(String, bool, String)> = VecDeque::new();
+    process_queue.push_back(("broadcaster".to_string(), false, "".to_string()));
+    let mut low_pulses: usize = 0;
+    let mut high_pulses: usize = 0;
+
+    while let Some((module_name, input, sender)) = process_queue.pop_front() {
+        match input {
+            true => high_pulses += 1,
+            false => low_pulses += 1,
+        }
+        if let Some(module) = modules.get_mut(&module_name) {
+            match module {
+                Module::FlipFlop { state, dests } => {
+                    if !input {
+                        let flipped = !(*state);
+                        *state = flipped;
+                        for dest in dests {
+                            process_queue.push_back((dest.clone(), state.clone(), module_name.clone()));
+                        }
+                    }
+                },
+                Module::Conjunction { state, dests } => {
+                    let stored = state.get_mut(&sender.to_string()).unwrap();
+                    *stored = input;
+
+                    let mut send = true;
+                    if state.values().all(|x| *x) {
+                        send = false;
+                    }
+                    for dest in dests {
+                        process_queue.push_back((dest.clone(), send, module_name.clone()));
+                    }
+                },
+                Module::Broadcast { dests } => {
+                    for dest in dests {
+                        process_queue.push_back((dest.clone(), input, module_name.clone()));
+                    }
+                },
+            }
+        }
+    }
+
+    return (high_pulses, low_pulses)
+}
+
+#[aoc(day20, part2)]
+fn part2(og_modules: &HashMap<String, Module>) -> usize {
+    let mut lcm = vec![];
+    let before = ["tr", "xm", "dr", "nh"];
+
+    for module_name in before {
+        let mut modules = og_modules.clone();
+        let mut count: usize = 1;
+        while !push_the_button_part2(&mut modules, module_name.to_string()) {
+            count += 1;
+        }
+        lcm.push(count);
+    }
+
+    println!("{:?}", lcm);
+
+    let lcm = lcm.iter()
+        .cloned()
+        .reduce(|a, b| a.lcm(&b))
+        .unwrap();
+
+    lcm
+}
+
+fn push_the_button_part2(modules: &mut HashMap<String, Module>, to_find: String) -> bool {
+    let mut process_queue: VecDeque<(String, bool, String)> = VecDeque::new();
+    process_queue.push_back(("broadcaster".to_string(), false, "".to_string()));
+
+    while let Some((module_name, input, sender)) = process_queue.pop_front() {
+        if module_name == to_find && input == false {
+            return true
+        }
+        if let Some(module) = modules.get_mut(&module_name) {
+            match module {
+                Module::FlipFlop { state, dests } => {
+                    if !input {
+                        let flipped = !(*state);
+                        *state = flipped;
+                        for dest in dests {
+                            process_queue.push_back((dest.clone(), state.clone(), module_name.clone()));
+                        }
+                    }
+                },
+                Module::Conjunction { state, dests } => {
+                    let stored = state.get_mut(&sender.to_string()).unwrap();
+                    *stored = input;
+
+                    let mut send = true;
+                    if state.values().all(|x| *x) {
+                        send = false;
+                    }
+                    for dest in dests {
+                        process_queue.push_back((dest.clone(), send, module_name.clone()));
+                    }
+                },
+                Module::Broadcast { dests } => {
+                    for dest in dests {
+                        process_queue.push_back((dest.clone(), input, module_name.clone()));
+                    }
+                },
+            }
+        }
+    }
+
+    return false
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const EX_1: &str = r"broadcaster -> a, b, c
+%a -> b
+%b -> c
+%c -> inv
+&inv -> a";
+
+const EX_2: &str = r"broadcaster -> a
+%a -> inv, con
+&inv -> b
+%b -> con
+&con -> rx";
+
+    #[test]
+    fn part1_example1() {
+        assert_eq!(part1(&parse(EX_1)), 32000000);
+    }
+
+
+
+    #[test]
+    fn part1_example2() {
+        assert_eq!(part1(&parse(EX_2)), 11687500);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse(EX_2)), 1);
+    }
+}

src/lib.rs

@@ -1,3 +1,4 @@
+mod day20;
 mod day19;
 mod day18;
 mod day17;