1 files changed, 102 insertions, 0 deletions
diff --git a/2020/src/bin/day_6.rs b/2020/src/bin/day_6.rs
new file mode 100644
index 0000000..68efbce
--- /dev/null
+++ b/2020/src/bin/day_6.rs
@@ -0,0 +1,102 @@
+use bevy::prelude::*;
+use std::collections::{BTreeMap, BTreeSet};
+use std::fs::File;
+use std::io::{BufRead, BufReader};
+
+fn main() {
+    App::build()
+        .add_resource(WindowDescriptor {
+            title: "Advent of Code".to_string(),
+            width: 1920,
+            height: 1080,
+            ..Default::default()
+        })
+        .add_resource(ClearColor(Color::rgb(0., 0., 0.)))
+        .add_startup_system(setup_camera.system())
+        .add_startup_system(read_input_file.system())
+        .add_stage("calculate")
+        .add_system_to_stage("calculate", calculate_anyone_groups.system())
+        .add_system_to_stage("calculate", calculate_everyone_groups.system())
+        .add_stage("report")
+        .add_system_to_stage("report", count_anyone_group_sizes.system())
+        .add_system_to_stage("report", count_everyone_group_sizes.system())
+        //.add_plugins(DefaultPlugins)
+        .run();
+}
+
+fn setup_camera(mut commands: Commands) {
+    commands.spawn(Camera2dComponents::default());
+}
+
+struct Individual;
+struct Anyone;
+struct Everyone;
+
+struct Group(usize);
+struct Answers(BTreeSet<char>);
+
+fn read_input_file(mut commands: Commands) {
+    let f = File::open("./inputs/day_6.txt").unwrap();
+
+    let mut current_group = 0;
+    for line in BufReader::new(f).lines() {
+        let line = line.unwrap();
+        let line = line.trim();
+        if line.is_empty() {
+            current_group += 1;
+        } else {
+            let answers = line.chars().collect();
+            commands.spawn((Individual, Group(current_group), Answers(answers)));
+        }
+    }
+}
+
+fn calculate_anyone_groups(
+    mut commands: Commands,
+    individuals: Query<With<Individual, (&Group, &Answers)>>,
+) {
+    let mut anyone_groups = BTreeMap::new();
+    for (group_id, answer) in individuals.iter() {
+        let updated = anyone_groups
+            .entry(group_id.0)
+            .or_insert(BTreeSet::new())
+            .union(&answer.0)
+            .cloned()
+            .collect();
+        anyone_groups.insert(group_id.0, updated);
+    }
+
+    for (group_id, anyone) in anyone_groups.into_iter() {
+        commands.spawn((Anyone, Group(group_id), Answers(anyone)));
+    }
+}
+
+fn calculate_everyone_groups(
+    mut commands: Commands,
+    individuals: Query<With<Individual, (&Group, &Answers)>>,
+) {
+    let mut anyone_groups = BTreeMap::new();
+    for (group_id, answer) in individuals.iter() {
+        let updated = anyone_groups
+            .entry(group_id.0)
+            .or_insert(answer.0.clone())
+            .intersection(&answer.0)
+            .cloned()
+            .collect();
+        anyone_groups.insert(group_id.0, updated);
+    }
+
+    for (group_id, anyone) in anyone_groups.into_iter() {
+        commands.spawn((Everyone, Group(group_id), Answers(anyone)));
+    }
+}
+
+fn count_anyone_group_sizes(groups: Query<With<Anyone, &Answers>>) {
+    let sum: usize = groups.iter().map(|g| g.0.len()).sum();
+    println!("Anyone: {}", sum);
+}
+
+fn count_everyone_group_sizes(groups: Query<With<Everyone, &Answers>>) {
+    let sum: usize = groups.iter().map(|g| g.0.len()).sum();
+    println!("Everyone: {}", sum);
+}