1 files changed, 82 insertions, 0 deletions
diff --git a/2024/day11.rs b/2024/day11.rs
new file mode 100644
index 0000000..0730c5f
--- /dev/null
+++ b/2024/day11.rs
@@ -0,0 +1,82 @@
+#![allow(dead_code)]
+#![allow(unused_variables)]
+#![allow(unused_mut)]
+use std::collections::HashMap;
+use std::env;
+use std::fs::File;
+use std::io::Read;
+
+fn evolve(s: &Vec<u64>) -> Vec<u64> {
+    let mut sn: Vec<u64> = Vec::new();
+
+    for n in s {
+        if *n == 0 {
+            sn.push(1);
+        } else if n.checked_ilog(10).unwrap() % 2 == 1 {
+            let pow = 10_u64.pow(n.checked_ilog(10).unwrap() / 2 + 1);
+            sn.push(n / pow);
+            sn.push(n % pow);
+        } else {
+            sn.push(n * 2024);
+        }
+    }
+    return sn;
+}
+
+fn evolve_fast(n: u64, depth: u64, depth_end: u64, lut: &mut HashMap<(u64, u64), u64>) -> u64 {
+    if depth == depth_end {
+        return 1;
+    }
+
+    if let Some(val) = lut.get(&(n, depth)) {
+        return *val;
+    }
+
+    let sum = if n == 0 {
+        evolve_fast(1, depth + 1, depth_end, lut)
+    } else if n.checked_ilog(10).unwrap() % 2 == 1 {
+        let pow = 10_u64.pow(n.checked_ilog(10).unwrap() / 2 + 1);
+        let a = evolve_fast(n / pow, depth + 1, depth_end, lut);
+        let b = evolve_fast(n % pow, depth + 1, depth_end, lut);
+        a + b
+    } else {
+        evolve_fast(n * 2024, depth + 1, depth_end, lut)
+    };
+
+    lut.insert((n, depth), sum);
+
+    return sum;
+}
+
+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 line = content.trim_end().split("\n").next().unwrap();
+
+    let stones: Vec<u64> = line.split(" ").map(|a| a.parse().unwrap()).collect();
+
+    let mut s = stones.clone();
+    for i in 0..25 {
+        s = evolve(&s);
+    }
+    let res1 = s.len();
+
+    let mut s2 = stones.clone();
+    let mut res2 = 0;
+    let mut hm = HashMap::new();
+    for n in s2 {
+        res2 += evolve_fast(n, 0, 75, &mut hm);
+    }
+
+    println!("res1: {}", res1);
+    println!("res2: {}", res2);
+    assert_eq!(res1, 220722);
+    assert_eq!(res2, 261952051690787);
+}