✨ Day 8

README.md

@@ -3,8 +3,8 @@
 [![About](https://img.shields.io/badge/Advent%20of%20Code-2024-brightgreen?style=flat-square)](https://adventofcode.com/2024/about)
 [![Language: Rust](https://img.shields.io/badge/Language-Rust-orange.svg?style=flat-square)](https://en.wikipedia.org/wiki/Rust_(programming_language))
 [![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg?style=flat-square)](https://mit-license.org/)
-![Days completed](https://img.shields.io/badge/Days%20completed-5%20%2B%202%20half-red?style=flat-square)
-![Stars](https://img.shields.io/badge/Stars-12-yellow?style=flat-square)
+![Days completed](https://img.shields.io/badge/Days%20completed-6%20%2B%202%20half-red?style=flat-square)
+![Stars](https://img.shields.io/badge/Stars-14-yellow?style=flat-square)
 
 > ⚠️ This README is copied from my previous years solution. It is not fully adopted to 2024 yet.
 

src/days/d08.rs

@@ -1,32 +1,209 @@
+use std::{
+    collections::{HashMap, HashSet},
+    ops::{Add, Mul, Sub},
+};
+
 use super::{Answer, Day, DayImpl};
 
 const CURRENT_DAY: u8 = 8;
 
-type Data = Vec<u64>;
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+struct Vector {
+    pub x: i64,
+    pub y: i64,
+}
+
+impl Sub for Vector {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self::Output {
+        Self {
+            x: self.x - rhs.x,
+            y: self.y - rhs.y,
+        }
+    }
+}
+
+impl Add for Vector {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self::Output {
+        Self {
+            x: self.x + rhs.x,
+            y: self.y + rhs.y,
+        }
+    }
+}
+
+impl Mul for Vector {
+    type Output = Self;
+
+    fn mul(self, rhs: Self) -> Self::Output {
+        Self {
+            x: self.x * rhs.x,
+            y: self.y * rhs.y,
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct AntennaMap {
+    antenna: HashMap<char, Vec<Vector>>,
+    limits: Vector,
+}
+
+impl AntennaMap {
+    fn is_in_limits(&self, point: Vector) -> bool {
+        !(point.x < 0 || point.y < 0 || point.x >= self.limits.x || point.y >= self.limits.y)
+    }
+
+    fn get_antinodes(&self, frequency: char) -> Option<Vec<Vector>> {
+        let antennas = self.antenna.get(&frequency)?;
+        let antenna_count = antennas.len();
+
+        if antenna_count < 2 {
+            return Some(vec![]);
+        }
+
+        let mut antinodes = Vec::with_capacity(antenna_count.pow(2) - antenna_count);
+
+        for a in 0..antenna_count {
+            for b in (0..antenna_count).filter(|v| *v != a) {
+                let new_position =
+                    antennas[a] + (antennas[b] - antennas[a]) * Vector { x: 2, y: 2 };
+                if self.is_in_limits(new_position) {
+                    antinodes.push(new_position);
+                }
+            }
+        }
+
+        Some(antinodes)
+    }
+
+    fn get_resonances(&self, frequency: char) -> Option<Vec<Vector>> {
+        let antennas = self.antenna.get(&frequency)?;
+        let antenna_count = antennas.len();
+
+        if antenna_count < 2 {
+            return Some(vec![]);
+        }
+
+        let mut antinodes = Vec::with_capacity(antenna_count.pow(2) - antenna_count);
+
+        for a in 0..antenna_count {
+            for b in (0..antenna_count).filter(|v| *v != a) {
+                let distance = antennas[b] - antennas[a];
+
+                let mut multiplier = 1; // WHYYYY does this have to be 1.... that's just dumb
+
+                loop {
+                    let new_position = antennas[a]
+                        + distance
+                            * Vector {
+                                x: multiplier,
+                                y: multiplier,
+                            };
+                    if !self.is_in_limits(new_position) {
+                        break;
+                    }
+                    antinodes.push(new_position);
+                    multiplier += 1;
+                }
+            }
+        }
+
+        Some(antinodes)
+    }
+
+    fn get_all_antinodes(&self) -> Vec<Vector> {
+        self.antenna
+            .keys()
+            .filter_map(|frequency| self.get_antinodes(*frequency))
+            .flatten()
+            .collect()
+    }
+
+    fn get_all_resonances(&self) -> Vec<Vector> {
+        self.antenna
+            .keys()
+            .filter_map(|frequency| self.get_resonances(*frequency))
+            .flatten()
+            .collect()
+    }
+}
+
+impl From<&str> for AntennaMap {
+    fn from(value: &str) -> Self {
+        let lines = value.lines();
+
+        let limits = Vector {
+            y: lines.clone().count() as i64,
+            x: lines.clone().next().unwrap().len() as i64,
+        };
+
+        Self {
+            antenna: lines
+                .enumerate()
+                .map(|(y, line)| {
+                    (
+                        y,
+                        line.chars()
+                            .enumerate()
+                            .filter(|(_, char)| *char != '.')
+                            .collect::<Vec<_>>(),
+                    )
+                })
+                .filter(|(_, line)| line.len() > 0)
+                .fold(HashMap::new(), |mut map, (y, line)| {
+                    line.into_iter().for_each(|(x, frequency)| {
+                        if let Some(antenna) = map.get_mut(&frequency) {
+                            antenna.push(Vector {
+                                x: x as i64,
+                                y: y as i64,
+                            });
+                        } else {
+                            map.insert(frequency, vec![Vector {
+                                x: x as i64,
+                                y: y as i64,
+                            }]);
+                        }
+                    });
+                    map
+                }),
+            limits: limits,
+        }
+    }
+}
+
+type Data = AntennaMap;
 impl DayImpl<Data> for Day<CURRENT_DAY> {
     fn init_test() -> (Self, Data) {
         Self::init(include_str!("test_inputs/test08.txt"))
     }
 
     fn expected_results() -> (Answer, Answer) {
-        (Answer::Number(0), Answer::Number(0))
+        (Answer::Number(14), Answer::Number(34))
     }
 
     fn init(input: &str) -> (Self, Data) {
-        (
-            Self {},
-            input
-                .lines()
-                .map(|v| v.parse::<u64>().expect("error while parsing input."))
-                .collect(),
-        )
+        (Self {}, input.into())
     }
 
     fn one(&self, data: &mut Data) -> Answer {
-        Answer::Number(data.len() as u64)
+        Answer::Number(
+            data.get_all_antinodes()
+                .into_iter()
+                .collect::<HashSet<Vector>>()
+                .len() as u64,
+        )
     }
 
     fn two(&self, data: &mut Data) -> Answer {
-        Answer::Number(data.len() as u64)
+        Answer::Number(
+            data.get_all_resonances()
+                .into_iter()
+                .collect::<HashSet<Vector>>()
+                .len() as u64,
+        )
     }
 }

src/days/test_inputs/test08.txt

@@ -0,0 +1,12 @@
+............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............