day8

aoc_2024/src/day3.rs

@@ -52,6 +52,10 @@ mod tests {
             )),
             161
         );
+        assert_eq!(
+            part1(&parse(include_str!("../input/2024/day3.txt"))),
+            191183308
+        );
     }
 
     #[test]
@@ -62,5 +66,9 @@ mod tests {
             )),
             48
         );
+        assert_eq!(
+            part2(&parse(include_str!("../input/2024/day3.txt"))),
+            92082041
+        );
     }
 }

aoc_2024/src/day8.rs

@@ -0,0 +1,117 @@
+use std::collections::{HashMap, HashSet};
+
+use aoc_runner_derive::{aoc, aoc_generator};
+use num::integer::gcd;
+
+type Input = ((isize, isize), Vec<Vec<(isize, isize)>>);
+
+#[aoc_generator(day8)]
+fn parse(input: &str) -> Input {
+    let mut map = HashMap::new();
+    let h = input.lines().count();
+    let w = input.lines().find(|_| true).unwrap().len();
+    input.lines().enumerate().for_each(|(y, line)| {
+        line.chars()
+            .enumerate()
+            .filter(|(_, c)| c != &'.')
+            .for_each(|(x, c)| {
+                if let std::collections::hash_map::Entry::Vacant(e) = map.entry(c) {
+                    e.insert(vec![(x as isize, y as isize)]);
+                } else {
+                    map.get_mut(&c).unwrap().push((x as isize, y as isize));
+                }
+            });
+    });
+    let vec = map.into_values().collect();
+    ((w as isize, h as isize), vec)
+}
+
+#[aoc(day8, part1)]
+fn part1(input: &Input) -> usize {
+    let mut set = HashSet::new();
+    input.1.iter().for_each(|vec| {
+        for l in 0..vec.len() {
+            for r in l + 1..vec.len() {
+                let a1 = vec[l];
+                let a2 = vec[r];
+                let c1 = (2 * a1.0 - a2.0, 2 * a1.1 - a2.1);
+                let c2 = (2 * a2.0 - a1.0, 2 * a2.1 - a1.1);
+                if c1.0 >= 0 && c1.0 < input.0 .0 && c1.1 >= 0 && c1.1 < input.0 .1 {
+                    set.insert(c1);
+                }
+                if c2.0 >= 0 && c2.0 < input.0 .0 && c2.1 >= 0 && c2.1 < input.0 .1 {
+                    set.insert(c2);
+                }
+            }
+        }
+    });
+    set.len()
+}
+
+#[aoc(day8, part2)]
+fn part2(input: &Input) -> usize {
+    let mut set = HashSet::new();
+    input.1.iter().for_each(|vec| {
+        for l in 0..vec.len() {
+            for r in l + 1..vec.len() {
+                let a1 = vec[l];
+                let a2 = vec[r];
+                let s = a1;
+                let v = (a2.0 - a1.0, a2.1 - a1.1);
+                let v = (v.0 / gcd(v.0, v.1), v.1 / gcd(v.0, v.1));
+                let mut d = 0;
+                loop {
+                    let c = (s.0 + d * v.0, s.1 + d * v.1);
+                    d += 1;
+                    if c.0 >= 0 && c.0 < input.0 .0 && c.1 >= 0 && c.1 < input.0 .1 {
+                        set.insert(c);
+                    } else {
+                        break;
+                    }
+                }
+                let mut d = 0;
+                loop {
+                    let c = (s.0 + d * v.0, s.1 + d * v.1);
+                    d -= 1;
+                    if c.0 >= 0 && c.0 < input.0 .0 && c.1 >= 0 && c.1 < input.0 .1 {
+                        set.insert(c);
+                    } else {
+                        break;
+                    }
+                }
+            }
+        }
+    });
+    // for y in 0..input.0 .1 {
+    //     println!();
+    //     for x in 0..input.0 .0 {
+    //         print!("{}", if set.contains(&(x, y)) { '#' } else { '.' })
+    //     }
+    // }
+    set.len()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(
+            part1(&parse(
+                "............\n........0...\n.....0......\n.......0....\n....0.......\n......A.....\n............\n............\n........A...\n.........A..\n............\n............"
+            )),
+            14
+        );
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(
+            part2(&parse(
+                "............\n........0...\n.....0......\n.......0....\n....0.......\n......A.....\n............\n............\n........A...\n.........A..\n............\n............"
+            )),
+            34
+        );
+    }
+}

aoc_2024/src/lib.rs

@@ -1,3 +1,4 @@
+mod day8;
 mod day1;
 mod day2;
 mod day3;