day06

1 files changed, 89 insertions, 0 deletions

diff --git a/2024/day06.rs b/2024/day06.rs
new file mode 100644
index 0000000..7a31743
--- /dev/null
+++ b/2024/day06.rs
@@ -0,0 +1,89 @@
+#![allow(dead_code)]
+#![allow(unused_variables)]
+#![allow(unused_mut)]
+use std::collections::HashSet;
+use std::env;
+use std::fs::File;
+use std::io::Read;
+
+fn run(
+    mut pos: (i32, i32),
+    m: &Vec<Vec<bool>>,
+) -> (bool, HashSet<(i32, i32)>, HashSet<((i32, i32), (i32, i32))>) {
+    let mut hs: HashSet<(i32, i32)> = HashSet::new();
+    let mut hs2: HashSet<((i32, i32), (i32, i32))> = HashSet::new();
+    let mut circ = false;
+    let mut dir = [(0, -1), (1, 0), (0, 1), (-1, 0)];
+    loop {
+        hs.insert(pos);
+        hs2.insert((pos, dir[0]));
+        let new_pos = (pos.0 + dir[0].0, pos.1 + dir[0].1);
+
+        if hs2.contains(&(new_pos, dir[0])) {
+            circ = true;
+            break;
+        }
+        if new_pos.0 < 0
+            || new_pos.1 < 0
+            || new_pos.0 >= m[0].len().try_into().unwrap()
+            || new_pos.1 >= m.len().try_into().unwrap()
+        {
+            break;
+        }
+        if m[new_pos.1 as usize][new_pos.0 as usize] {
+            pos = new_pos;
+            continue;
+        } else {
+            dir.rotate_left(1);
+        }
+    }
+
+    return (circ, hs, hs2);
+}
+
+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 = content.trim_end().split("\n");
+
+    let mut pos: (i32, i32) = (0, 0);
+    let mut m: Vec<Vec<bool>> = Vec::new();
+    for (y, line) in lines.enumerate() {
+        let mut row = Vec::new();
+        for (x, c) in line.chars().enumerate() {
+            row.push(if c == '#' { false } else { true });
+            if c == '^' {
+                pos = (x.try_into().unwrap(), y.try_into().unwrap());
+            }
+        }
+        m.push(row);
+    }
+
+    let (circ, hs, hs2) = run(pos, &m);
+    let res1 = hs.len();
+
+    let mut res2 = 0;
+    for y in 0..m.len() {
+        for x in 0..m[0].len() {
+            let mut m2 = m.clone();
+            m2[y][x] = false;
+            let (circ, hs, hs2) = run(pos, &m2);
+            if circ {
+                res2 += 1;
+                println!("circ {} {}", y, x);
+            }
+        }
+    }
+
+    println!("res1: {}", res1);
+    println!("res2: {}", res2);
+    assert_eq!(res1, 5531);
+    assert_eq!(res2, 2165);
+}