From a33020141fe1439209dd46e8caf29144bd4463f8 Mon Sep 17 00:00:00 2001
From: Justin Wernick <justin@worthe-it.co.za>
Date: Sat, 12 Dec 2020 19:30:30 +0200
Subject: Day 10

---
 src/bin/day_10.rs | 124 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)
 create mode 100644 src/bin/day_10.rs

(limited to 'src')

diff --git a/src/bin/day_10.rs b/src/bin/day_10.rs
new file mode 100644
index 0000000..7ef4fa2
--- /dev/null
+++ b/src/bin/day_10.rs
@@ -0,0 +1,124 @@
+use bevy::{app::AppExit, prelude::*};
+use std::io::{BufRead, BufReader};
+use std::{collections::BTreeMap, fs::File};
+
+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_startup_stage("differences")
+        .add_startup_system_to_stage("differences", add_min_differences.system())
+        .add_startup_system_to_stage("differences", add_all_differences.system())
+        .add_startup_stage("report")
+        .add_startup_system_to_stage("report", print_difference_stats.system())
+        .add_system(add_next_paths_to_end_sum.system())
+        .add_system(report_full_paths_to_end.system())
+        .add_plugins(DefaultPlugins)
+        .run();
+}
+
+fn setup_camera(mut commands: Commands) {
+    commands.spawn(Camera2dComponents::default());
+}
+
+#[derive(PartialEq, Eq, PartialOrd, Ord)]
+struct MinJoltDiff(i64);
+#[derive(Clone)]
+struct NextJolts(Vec<Entity>);
+struct Jolts(i64);
+struct PathsToEnd(u64);
+
+fn read_input_file(mut commands: Commands) {
+    let f = File::open("./inputs/day_10.txt").unwrap();
+
+    commands.spawn((Jolts(0),));
+    for line in BufReader::new(f).lines() {
+        let line = line.unwrap();
+        let line = line.trim();
+        let num = line.parse().unwrap();
+
+        commands.spawn((Jolts(num),));
+    }
+}
+
+fn add_min_differences(
+    mut commands: Commands,
+    jolts_query: Query<(Entity, &Jolts, Option<&MinJoltDiff>)>,
+) {
+    for (entity, jolts, jolt_diff) in jolts_query.iter() {
+        if jolt_diff.is_none() {
+            let min_increase = jolts_query
+                .iter()
+                .map(|(_, other_jolts, _)| other_jolts)
+                .filter(|other_jolts| other_jolts.0 > jolts.0)
+                .map(|other_jolts| MinJoltDiff(other_jolts.0 - jolts.0))
+                .min()
+                .unwrap_or(MinJoltDiff(3));
+            commands.insert_one(entity, min_increase);
+        }
+    }
+}
+
+fn add_all_differences(mut commands: Commands, jolts_query: Query<(Entity, &Jolts)>) {
+    for (entity, jolts) in jolts_query.iter() {
+        let next_entities = jolts_query
+            .iter()
+            .filter(|(_, other_jolts)| other_jolts.0 > jolts.0 && other_jolts.0 - jolts.0 <= 3)
+            .map(|(other_entity, _)| other_entity)
+            .collect();
+        commands.insert_one(entity, NextJolts(next_entities));
+    }
+}
+
+fn print_difference_stats(diffs: Query<&MinJoltDiff>) {
+    let mut buckets: BTreeMap<i64, usize> = BTreeMap::new();
+    for diff in diffs.iter() {
+        *buckets.entry(diff.0).or_insert(0) += 1;
+    }
+    println!("Buckets: {:?}", buckets);
+
+    println!(
+        "Bucket 1 * Bucket 3: {}",
+        buckets.get(&1).unwrap_or(&0) * buckets.get(&3).unwrap_or(&0)
+    );
+}
+
+fn add_next_paths_to_end_sum(
+    mut commands: Commands,
+    potential_to_add: Query<Without<PathsToEnd, (Entity, &NextJolts)>>,
+    already_added: Query<&PathsToEnd>,
+) {
+    for (entity, next) in potential_to_add.iter() {
+        if next.0.is_empty() {
+            commands.insert_one(entity, PathsToEnd(1));
+        } else {
+            let next_paths: Result<Vec<&PathsToEnd>, _> = next
+                .0
+                .iter()
+                .map(|next_entity| already_added.get(*next_entity))
+                .collect();
+            if let Ok(next_paths) = next_paths {
+                let sum = next_paths.iter().map(|paths| paths.0).sum();
+                commands.insert_one(entity, PathsToEnd(sum));
+            }
+        }
+    }
+}
+
+fn report_full_paths_to_end(
+    mut exit_events: ResMut<Events<AppExit>>,
+    jolts: &Jolts,
+    paths: &PathsToEnd,
+) {
+    if jolts.0 == 0 {
+        println!("Paths from the start to the end: {}", paths.0);
+        exit_events.send(AppExit);
+    }
+}
-- 
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