day 8

Cargo.lock

@@ -75,6 +75,7 @@ version = "0.1.0"
 dependencies = [
  "ansi_term",
  "clap",
+ "itertools",
  "paste",
  "regex",
  "thiserror",
@@ -126,6 +127,12 @@ version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5b63caa9aa9397e2d9480a9b13673856c78d8ac123288526c37d7839f2a86990"
 
+[[package]]
+name = "either"
+version = "1.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "60b1af1c220855b6ceac025d3f6ecdd2b7c4894bfe9cd9bda4fbb4bc7c0d4cf0"
+
 [[package]]
 name = "heck"
 version = "0.5.0"
@@ -138,6 +145,15 @@ version = "1.70.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7943c866cc5cd64cbc25b2e01621d07fa8eb2a1a23160ee81ce38704e97b8ecf"
 
+[[package]]
+name = "itertools"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "413ee7dfc52ee1a4949ceeb7dbc8a33f2d6c088194d9f922fb8318faf1f01186"
+dependencies = [
+ "either",
+]
+
 [[package]]
 name = "memchr"
 version = "2.7.4"

Cargo.toml

@@ -6,6 +6,7 @@
 [dependencies]
     ansi_term = "0.12"
     clap      = { version = "4", features = ["derive"] }
+    itertools = "0.13"
     paste     = "1"
     regex     = "1"
     thiserror = "2"

src/main.rs

@@ -29,6 +29,7 @@ fn main() -> Result<()> {
         5 => AocDayFiveSolution,
         6 => AocDaySixSolution,
         7 => AocDaySevenSolution,
+        8 => AocDayEightSolution,
     };
 
     Ok(())

src/solutions/day_4.rs

@@ -3,7 +3,7 @@ use std::{collections::HashMap, fs::read_to_string, path::Path};
 use super::AocSolution;
 use crate::utils::{coord::Coord, Result};
 
-const DIRS: [Coord; 8] = [
+const DIRS: [Coord<i16>; 8] = [
     Coord::new(1, 0),
     Coord::new(1, -1),
     Coord::new(0, -1),
@@ -15,7 +15,7 @@ const DIRS: [Coord; 8] = [
 ];
 
 struct XmasGrid {
-    pub grid: HashMap<Coord, char>,
+    pub grid: HashMap<Coord<i16>, char>,
 }
 
 impl XmasGrid {
@@ -29,7 +29,7 @@ impl XmasGrid {
         }
     }
 
-    fn find_xmas(&self, pos: Coord) -> usize {
+    fn find_xmas(&self, pos: Coord<i16>) -> usize {
         let mut tmp = 0;
         for dir in DIRS {
             let mut found = true;
@@ -51,7 +51,7 @@ impl XmasGrid {
         tmp
     }
 
-    fn find_x_mas(&self, pos: Coord) -> usize {
+    fn find_x_mas(&self, pos: Coord<i16>) -> usize {
         let (x, y) = (pos.x, pos.y);
 
         let tr = self.grid.get(&Coord::new(x + 1, y + 1));

src/solutions/day_6.rs

@@ -10,8 +10,8 @@ use crate::utils::{coord::Coord, direction::Direction, Result};
 #[derive(Debug, Clone)]
 struct Guard {
     dir: Direction,
-    cur: Coord,
-    grid: HashMap<Coord, bool>,
+    cur: Coord<i16>,
+    grid: HashMap<Coord<i16>, bool>,
 }
 
 impl Guard {

src/solutions/day_7.rs

@@ -1,4 +1,4 @@
-use std::{fs::read_to_string, ops::Mul, path::Path};
+use std::{fs::read_to_string, path::Path};
 
 use super::AocSolution;
 use crate::utils::Result;

src/solutions/day_8.rs

@@ -1,8 +1,87 @@
-use std::{fs::read_to_string, path::Path};
+use std::{collections::HashMap, fs::read_to_string, path::Path};
+
+use itertools::Itertools;
 
 use super::AocSolution;
-use crate::utils::Result;
+use crate::utils::{coord::Coord, Result};
 
+fn anticoord(a: Coord<i8>, b: Coord<i8>) -> (Coord<i8>, Coord<i8>) {
+    let delta = a - b;
+    (a + delta, b - delta)
+}
+
+struct Map {
+    pub antennas: HashMap<char, Vec<Coord<i8>>>,
+    pub grid: HashMap<Coord<i8>, bool>,
+}
+
+impl Map {
+    fn new(src: &str) -> Self {
+        let (antennas, grid) = src
+            .lines()
+            .zip(0..)
+            .flat_map(|(line, y)| {
+                line.chars()
+                    .zip(0..)
+                    .map(move |(ch, x)| (Coord::new(x, y), ch))
+            })
+            .fold(
+                (HashMap::new(), HashMap::new()),
+                |(mut antennas, mut map), (coord, ch)| {
+                    if ch != '.' {
+                        antennas.entry(ch).or_insert(Vec::new()).push(coord);
+                    }
+
+                    map.insert(coord, false);
+
+                    (antennas, map)
+                },
+            );
+
+        Self { antennas, grid }
+    }
+
+    fn locations(&mut self) -> u64 {
+        for freq in self.antennas.values() {
+            freq.iter()
+                .tuple_combinations::<(_, _)>()
+                .map(|(&a, &b)| anticoord(a, b))
+                .for_each(|(a, b)| {
+                    if let Some(flag) = self.grid.get_mut(&a) {
+                        *flag = true;
+                    }
+
+                    if let Some(flag) = self.grid.get_mut(&b) {
+                        *flag = true;
+                    }
+                });
+        }
+
+        self.grid.values().filter(|&&x| x).count() as u64
+    }
+
+    fn resonance(&mut self) -> u64 {
+        for freq in self.antennas.values() {
+            freq.iter()
+                .permutations(2)
+                .map(|v| (v[0], v[1]))
+                .filter(|(a, b)| a.ne(b))
+                .for_each(|(&a, &b)| {
+                    let dist = b - a;
+                    let mut anti = b;
+
+                    while let Some(flag) = self.grid.get_mut(&anti) {
+                        *flag = true;
+                        anti = anti + dist;
+                    }
+                });
+        }
+
+        self.grid.values().filter(|&&x| x).count() as u64
+    }
+}
+
+#[derive(Clone, Copy)]
 pub struct AocDayEightSolution;
 
 impl AocSolution for AocDayEightSolution {
@@ -11,15 +90,17 @@ impl AocSolution for AocDayEightSolution {
     fn get_input(&self, path: Option<&Path>) -> Result<String> {
         Ok(match path {
             Some(p) => read_to_string(p)?,
-            None => read_to_string("./input/day_day_8.txt")?,
+            None => read_to_string("./input/day_8.txt")?,
         })
     }
 
     fn part_one(&self, input: &str) -> Result<Self::Output> {
-        todo!()
+        let mut map = Map::new(input);
+        Ok(map.locations())
     }
 
     fn part_two(&self, input: &str) -> Result<Self::Output> {
-        todo!()
+        let mut map = Map::new(input);
+        Ok(map.resonance())
     }
 }

src/utils/coord.rs

@@ -1,29 +1,41 @@
-use std::ops::Add;
+use std::{
+    fmt::Debug,
+    hash::Hash,
+    ops::{Add, Sub},
+};
 
-use super::direction::Direction;
+use super::{direction::Direction, Unit};
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct Coord {
-    pub x: i16,
-    pub y: i16,
+pub struct Coord<U: Unit> {
+    pub x: U,
+    pub y: U,
 }
 
-impl Coord {
-    pub const fn new(x: i16, y: i16) -> Self {
+impl<U: Unit> Coord<U> {
+    pub const fn new(x: U, y: U) -> Self {
         Self { x, y }
     }
 }
 
-impl Add for Coord {
-    type Output = Coord;
+impl<U: Unit> Add for Coord<U> {
+    type Output = Coord<U>;
 
     fn add(self, rhs: Self) -> Self::Output {
         Self::new(self.x + rhs.x, self.y + rhs.y)
     }
 }
 
-impl Add<Direction> for Coord {
-    type Output = Coord;
+impl<U: Unit> Sub for Coord<U> {
+    type Output = Coord<U>;
+
+    fn sub(self, rhs: Self) -> Self::Output {
+        Self::new(self.x - rhs.x, self.y - rhs.y)
+    }
+}
+
+impl<U: Unit> Add<Direction> for Coord<U> {
+    type Output = Coord<U>;
 
     fn add(self, rhs: Direction) -> Self::Output {
         let tmp = rhs.lookahead();

src/utils/direction.rs

@@ -1,6 +1,6 @@
 use std::ops::{Neg, Not};
 
-use super::coord::Coord;
+use super::{coord::Coord, Unit};
 
 #[derive(Debug, Default, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum Direction {
@@ -34,12 +34,12 @@ impl Direction {
         *self = !*self
     }
 
-    pub fn lookahead(&self) -> Coord {
+    pub fn lookahead<U: Unit>(&self) -> Coord<U> {
         match self {
-            Self::Up => Coord::new(0, -1),
-            Self::Right => Coord::new(1, 0),
-            Self::Down => Coord::new(0, 1),
-            Self::Left => Coord::new(-1, 0),
+            Self::Up => Coord::new(0.into(), (-1).into()),
+            Self::Right => Coord::new(1.into(), 0.into()),
+            Self::Down => Coord::new(0.into(), 1.into()),
+            Self::Left => Coord::new((-1).into(), 0.into()),
         }
     }
 }

src/utils/macros.rs

@@ -11,3 +11,12 @@ macro_rules! map_solution {
         }
     };
 }
+
+#[macro_export]
+macro_rules! impl_unit_for_type {
+    ($($type:ty),+ $(,)?) => {
+        $(
+        impl $crate::utils::Unit for $type {}
+        )+
+    };
+}

src/utils/mod.rs

@@ -4,6 +4,9 @@ pub mod macros;
 pub mod coord;
 pub mod direction;
 
+mod unit;
+pub use unit::*;
+
 pub type Result<T> = std::result::Result<T, Error>;
 
 #[derive(thiserror::Error, Debug)]

src/utils/unit.rs

@@ -0,0 +1,12 @@
+use std::{
+    fmt::Debug,
+    hash::Hash,
+    ops::{Add, Sub},
+};
+
+pub trait Unit:
+    Debug + Clone + Copy + PartialEq + Eq + Hash + Add<Output = Self> + Sub<Output = Self> + From<i8>
+{
+}
+
+impl_unit_for_type!(i8, i16, i32, i64, i128);