day08

1 files changed, 99 insertions, 0 deletions

diff --git a/2024/day08.rs b/2024/day08.rs
new file mode 100644
index 0000000..30a1913
--- /dev/null
+++ b/2024/day08.rs
@@ -0,0 +1,99 @@
+#![allow(dead_code)]
+#![allow(unused_variables)]
+#![allow(unused_mut)]
+use itertools::Itertools;
+use std::collections::HashMap;
+use std::collections::HashSet;
+use std::env;
+use std::fs::File;
+use std::io::Read;
+
+fn get_antinodes(a: (i32, i32), b: (i32, i32)) -> Vec<(i32, i32)> {
+    let mut ans = Vec::new();
+    let (ax, ay) = (a.0, a.1);
+    let (bx, by) = (b.0, b.1);
+    let dx = bx - ax;
+    let dy = by - ay;
+    ans.push((bx + dx, by + dy));
+    ans.push((ax - dx, ay - dy));
+    return ans;
+}
+
+fn bounded(min: i32, max: i32, val: i32) -> bool {
+    min <= val && val < max
+}
+
+fn get_antinodes2(xmax: i32, ymax: i32, a: (i32, i32), b: (i32, i32)) -> Vec<(i32, i32)> {
+    let mut ans = Vec::new();
+    let (ax, ay) = (a.0, a.1);
+    let (bx, by) = (b.0, b.1);
+    let dx = bx - ax;
+    let dy = by - ay;
+
+    ans.push((ax, ay));
+    ans.push((bx, by));
+
+    for n in 1.. {
+        let (ux, uy) = (bx + n * dx, by + n * dy);
+        if !bounded(0, xmax, ux) || !bounded(0, ymax, uy) {
+            break;
+        }
+        ans.push((ux, uy));
+    }
+
+    for n in 1.. {
+        let (ux, uy) = (ax - n * dx, ay - n * dy);
+        if !bounded(0, xmax, ux) || !bounded(0, ymax, uy) {
+            break;
+        }
+        ans.push((ux, uy));
+    }
+    return ans;
+}
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+    let filename = if args.len() == 1 {
+        "in/".to_owned() + args[0].split('/').last().unwrap() + ".pzl"
+    } else {
+        args[1].clone()
+    };
+    let mut f = File::open(filename).expect("cannot open file");
+    let mut content = String::new();
+    f.read_to_string(&mut content).expect("cannot read file");
+    let lines: Vec<_> = content.trim_end().split("\n").collect();
+
+    let ymax = lines.len() as i32;
+    let xmax = lines[0].len() as i32;
+
+    let mut hm: HashMap<char, Vec<(i32, i32)>> = HashMap::new();
+    for (y, line) in lines.iter().enumerate() {
+        for (x, c) in line.chars().enumerate() {
+            if c != '.' {
+                hm.entry(c).or_default().push((x as i32, y as i32));
+            }
+        }
+    }
+
+    let mut antinodes: HashSet<(i32, i32)> = HashSet::new();
+    let mut antinodes2: HashSet<(i32, i32)> = HashSet::new();
+    for (key, val) in hm.clone().into_iter() {
+        for (a, b) in val.clone().into_iter().tuple_combinations() {
+            for (x, y) in get_antinodes(a, b) {
+                if bounded(0, xmax, x) && bounded(0, ymax, y) {
+                    antinodes.insert((x, y));
+                }
+            }
+            for (x, y) in get_antinodes2(xmax, ymax, a, b) {
+                antinodes2.insert((x, y));
+            }
+        }
+    }
+    let res1 = antinodes.len();
+    let res2 = antinodes2.len();
+
+    println!("res1: {}", res1);
+    println!("res2: {}", res2);
+    assert_eq!(res1, 293);
+    assert_eq!(res2, 934);
+}