1 files changed, 103 insertions, 0 deletions
diff --git a/2024/day10.rs b/2024/day10.rs
new file mode 100644
index 0000000..7c8576d
--- /dev/null
+++ b/2024/day10.rs
@@ -0,0 +1,103 @@
+#![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 dfs(x0: i64, y0: i64, map: &Vec<Vec<i64>>, mut hs: HashSet<(i64, i64)>) -> HashSet<(i64, i64)> {
+    //println!("{} {}", x0, y0);
+    let h = map.len() as i64;
+    let w = map[0].len() as i64;
+
+    let n = map[y0 as usize][x0 as usize];
+    if n == 9 {
+        hs.insert((y0, x0));
+        return hs;
+    }
+
+    for (dx, dy) in [(0, 1), (0, -1), (1, 0), (-1, 0)] {
+        let x = x0 + dx as i64;
+        let y = y0 + dy as i64;
+        if (0 <= x) && (x < w) && (0 <= y) && (y < h) {
+            if map[y as usize][x as usize] == n + 1 {
+                hs = dfs(x, y, map, hs);
+            }
+        }
+    }
+    return hs;
+}
+
+fn dfs2(
+    x0: i64,
+    y0: i64,
+    map: &Vec<Vec<i64>>,
+    mut path: Vec<(i64, i64)>,
+    mut hs: HashSet<Vec<(i64, i64)>>,
+) -> HashSet<Vec<(i64, i64)>> {
+    //println!("{} {}", x0, y0);
+    let h = map.len() as i64;
+    let w = map[0].len() as i64;
+
+    path.push((x0, y0));
+
+    let n = map[y0 as usize][x0 as usize];
+    if n == 9 {
+        hs.insert(path);
+        return hs;
+    }
+
+    for (dx, dy) in [(0, 1), (0, -1), (1, 0), (-1, 0)] {
+        let x = x0 + dx as i64;
+        let y = y0 + dy as i64;
+        if (0 <= x) && (x < w) && (0 <= y) && (y < h) {
+            if map[y as usize][x as usize] == n + 1 {
+                hs = dfs2(x, y, map, path.clone(), hs);
+            }
+        }
+    }
+    return hs;
+}
+
+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 trailheads: Vec<(i64, i64)> = Vec::new();
+    let mut map: Vec<Vec<i64>> = Vec::new();
+    for (y, line) in lines.enumerate() {
+        let mut l: Vec<i64> = Vec::new();
+        for (x, c) in line.chars().enumerate() {
+            let n = c.to_digit(10).unwrap() as i64;
+            l.push(n);
+            if n == 0 {
+                trailheads.push((x as i64, y as i64));
+            }
+        }
+        map.push(l);
+    }
+
+    let mut res1 = 0;
+    let mut res2 = 0;
+    for (x0, y0) in trailheads {
+        let hs = dfs(x0, y0, &map, HashSet::new());
+        res1 += hs.len();
+
+        let hs2 = dfs2(x0, y0, &map, Vec::new(), HashSet::new());
+        res2 += hs2.len();
+    }
+
+    println!("res1: {}", res1);
+    println!("res2: {}", res2);
+    assert_eq!(res1, 607);
+    assert_eq!(res2, 1384);
+}